Amp and receiver advice for new B&W speakers

[jmasud]

Hi,

I’m new to hi-end hi fi and joined this forum to get some advice, as selecting the right system can get pretty confusing. I’ve been shopping around and have narrowed down some choices, but am still a bit confused and hope I can benefit from some expert opinion.

I want to essentially replace a standard Sony home theatre setup with a new TV and, more importantly, a better sound system. The Sony, of course, was barely adequate for movies, but it was torture using it for audio recordings, so I’m looking for an entirely different set up now: good speakers, with high-end hi fi and AV components. Will upgrade to a 65” flat panel LED or OLED (willing to wait for this year’s models), but want to go ahead with the rest of the purchases now.

First, a word about my room layout, since it is peculiar (about 24 x 26 ft). I have a long couch facing a floor-to-ceiling bookshelf which houses the TV and stereo components, along with the front and center speakers, which are about 16-17 ft from my normal watching position on the couch. The couch is about 5-6 ft away from the back wall, so there’s room to put rear speakers against the wall, about 13-14 ft apart. However, I only have space for bookshelf front speakers, although can have floor standing ones at the rear. The room also has other seating in front facing the other way, about 18 ft from the rear wall, which I use when listening to music. So I would like to use the floor standing speakers mainly for music (connected to Sonos, an Oppo BD 95 BluRay/CD player and other source inputs), but as rear speakers in a 5.1 ch home theatre environment when watching movies. I can place the sub wherever it works best in this configuration (am advised on a front corner location).

Now in terms of the equipment options, I’m pretty much sold on the B&W for the speakers: a pair of CM10 S2s for music and as rear HT speakers; a CMC and ASW10CM center and sub; and either a pair of CM5 S2 or PM1 for the front HT speakers. For the record, the other rear floor/front bookshelf/center/sub speaker combos I considered were Focus Aria 948/906/CC900/REL218 and Martin Logan Theos/Motion 35XT/Motif X/Dynamo 1000. Where I live, I will not be able to demo each combination, so am essentially making what I think is a safe choice based on brand reputation and reviews, plus I really prefer the B&W aesthetically over the rest (I know this should not be a deciding factor, but in my living room, it is!).

So, given these speakers, I’m now in a bit of a conundrum regarding the remaining components. Initially, the B&W vendor had suggested the following Rotel components (same parent company as B&W) in a package deal that at the time I thought was wholly adequate: RSX1562 7.1 ch HT AV receiver, RC 1570 stereo preamp, and RB 1582 200W 2 ch power amp. However, I now think the AV receiver is a bit dated (no Dolby Atmos, no HDMI 2.0, no HDCP 2.2, etc.), and the amp could also be upgraded. For the receiver, I’m now looking at the Denon AVR x7200W (which has all the bells and whistles missing in the Rotel, so is forward compliant with my proposed 4k TV). For the amp, I’m leaning towards the Quad Elite QMP mono blocks, with 260W per channel. I also could go for the Anthem A5 (5x225W), PVA7 (7x125W), or PVA 8 (8x125W) power amplifiers.

Here’s where I need help: I was thinking of using the AVR pre-outs to drive the power amp connected to the main music CM10 speakers, and using its built-in amp for the front, center and sub. Is this a workable solution, specially without a separate preamp for the main speakers, or would I be compromising both the home theatre and the music experience in the process (I’m getting conflicting views on this from salespersons I’ve spoken to)?

In terms of the amps, I’m sure the Quad mono blocks would be the best choice, although I would have a problem with their non-standard form factor (the 17”-inch wide Rotel components would have stacked very neatly on my shelf). However, this is not a deal breaker in case the QMPs are definitely a better choice over the Rotel and Anthem alternatives. I know matching the amps with the speakers is critical, so would really need some assistance here. If a separate preamp is imperative, will the RC 1570/RB 1582 combination do or should I pair a different preamp with the QMP (possibly a matched Quad Elite Pre?).

Finally, would it be worth splurging a little extra on the PM1s instead of the CM5s as the front speakers? Would the former sound good driven by the AVR, or should they be hooked up to the power amp as well? I’m not sure if I’ll ever listen to music simultaneously from all four speakers, but now it could be a possibility!

Thanks so much for any help on offer. Please bear in mind that the choices above are, of course, dictated by an overall budget, but I’m willing to fork out an extra grand or so if that makes a huge difference.

 

[Swerd]

First of all, welcome to AH.

Before I take a stab at your questions, I am struggling to understand how you plan to arrange your audio system.

• Your room is 24×26 feet. One wall has a floor-to-ceiling bookshelf which will house the TV and the rest of your electronic gear.
• A long couch faces the bookshelves, about 16-17 feet away, and 5-6 feet away from the wall behind it.
• You plan on smaller bookshelf speakers as your front left, center, & right speakers for use in home theater with the TV.
• And you plan on floor standing speakers in the area behind the sofa. These speakers will function both as rear channel speakers for HT, and as a pair of speakers for 2-channel music. For music listening you plan on sitting on other seating facing the rear wall. These chairs apparently are between the couch and the bookshelf wall.

Is my understanding correct?

If so, I don't understand how you can use a home theater receiver (with or without an external 2-channel amp) to run all this. How can you use the floor standing speakers as rear speakers for home theater, and as front speakers for music? It is possible to use a HT receiver both for HT and 2-channel music, but not if you plan on listening only to the rear channel speakers for music as you propose. If someone knows of a HT receiver that allows for this, please speak up.

Also, a listening distance of 16-17 feet for home theater is large. I worry that small bookshelf speakers won't have enough volume for adequate listening levels that far away. Generally small bookshelf speakers, such as the B&W CM5 or PM1 (even less sensitive than the CM5), are less sensitive than the large floor standing CM10.

It isn't clear how far you will be sitting from the floor standing speakers for music listening. But the seating distance may or may not be a problem for that use as well.

 

[jmasud]

Hi Swerd,

Yes, your understanding of the room layout is spot on.

As for switching the CM10s from a rear HT to front music mode, I think the vendor was suggesting connecting the rear HT preouts on the AVR to the aux input on the RC1570 preamp, so I'm assuming I could use the preamp to select the source (HT, Sonos, BD/CD player) for the floor standing speakers. Would that work?

I agree with you regarding the front speakers, and am thinking of getting the CM6 s2 instead of the CM5/PM1. I do have a space constraint (in that only bookshelf speakers are an option for the front), so I hope these will be powerful enough.

Thanks in advance for your advice.

 

[markw]

Hi Swerd,

Yes, your understanding of the room layout is spot on.

As for switching the CM10s from a rear HT to front music mode, I think the vendor was suggesting connecting the rear HT preouts on the AVR to the aux input on the RC1570 preamp, so I'm assuming I could use the preamp to select the source (HT, Sonos, BD/CD player) for the floor standing speakers. Would that work?.

I'm not Swerd but here's my take on this: This will work but not without significant problems.

1) The rear channels will be going through two preamp stages. Not really a good thing.
2) For multi-channel, the volume levels are balanced relative to each other. When you change the volume level for the preamp, the multi-channel balance will be changed and will need to be rebalanced if you want to maintain the same balance.
3) The sources plugged into the 1570 will only play through the rear speakers. They will never play through the other speakers. You may wind up regretting this, particularly the BD player, which is multi0-channel by nature.

I agree with you regarding the front speakers, and am thinking of getting the CM6 s2 instead of the CM5/PM1. I do have a space constraint (in that only bookshelf speakers are an option for the front), so I hope these will be powerful enough.

The only job a speaker has is to move air in a room. The larger the room, the more air there is to move. A small driver moves small amounts of air. if you try to force a speaker to try to move more air than the laws of physics allow it sounds bad at best and, at worst, ceases to function. Would you try to tow a 4500 trailer with a Fiat 500?

 

[Swerd]

I agree with Mark's 3 points above. In addition…

As for switching the CM10s from a rear HT to front music mode, I think the vendor was suggesting connecting the rear HT preouts on the AVR to the aux input on the RC1570 preamp, so I'm assuming I could use the preamp to select the source (HT, Sonos, BD/CD player) for the floor standing speakers. Would that work?

Not in any way that I can imagine. It doesn't mean it's impossible, only that I don't see it based on the AV receivers I know.

Running the AVR preouts into the RC1570 preamp will deliver the rear channel signals, when you want to hear the signal for the front left and right channels. Download the owners manual for your receiver and read it carefully to see if this can be done.

If the sound sources are connected to the AVR, you will not be able select them through the RC1570 stereo preamp. I believe you need to rethink this whole scenario.

I agree with you regarding the front speakers, and am thinking of getting the CM6 s2 instead of the CM5/PM1. I do have a space constraint (in that only bookshelf speakers are an option for the front), so I hope these will be powerful enough.

Both the CM5 and CM6 have (at least) two problems. First, they both have a sensitivity rating of 88 dB. That means when fed a test tone driven at 1 watt, a microphone directly in front of the speaker 1 meter away registers 88 dB of sound loudness. Both speakers have the same size 165 mm woofer and the cabinets are similar size, so they should have the same sensitivity. The only difference I can see between them is how the tweeter is mounted. So, using the CM6 instead of the CM5 does not solve the problem. Also, because there is no standard in how speaker sensitivity is reported, I wonder if 88 dB is too optimistic for smaller 2-way speakers. In my experience, 84-86 dB is more what I expect.

Second, both speakers have a bass vent mounted on the rear of the cabinet. If you place them in an enclosed space like on a built-in bookshelf, they will sound wrong. They will lack bass, and, independent of the vent issue, the all-important mid range will also sound different because the speaker is so close to the wall. Most speakers are designed to be located in a room "somewhat" distant from walls behind them and to the sides. Of course, how far varies with each owner and room, but moving them further away from reflecting surfaces, like walls, usually creates a more clear sound with better imaging of musicians or singers.

The PM1 does have the vent in front, but they are less sensitive at 84 dB. And, they will still suffer from being too close to the wall, as I described above for the CM5 or 6.

A third problem you may (or may not) have comes because these speakers have the so-called famous B&W yellow Kevlar mid woofer. These drivers have a noticeably characteristic sound that comes from a high-frequency resonance (aka noise) they produce. Because B&W chooses to cross these mid woofers over to the tweeter at an unusually high frequency of 4000 Hz, you can often hear this noise, even though its higher than the crossover point. It depends on the music selection, and how loud you listen. Some describe this sound as "unusually detailed" while others call it "edgy or harsh".

If you use either the CM5 or CM6 and listen at a distance of 16-17 feet, you will have to turn up the volume to achieve normal listening levels. That should increase the chances of hearing the Kevlar noise. Some people own B&W speakers and love them, while others object to the high frequency harshness. It does take time for owners to become aware of this problem. I only point this out because the high volumes that your room might require could make this more apparent for you than for others in other rooms.

 

[Swerd]

I believe you need to rethink this whole scenario.

When you read an AVR's manual, focus on its multi-room or multi-zone functions.

If you think of your 5 channel sound and TV as the main zone, and your music-only 2-channel listening as zone 2, you might find a solution to your problem.

The Denon you mentioned is capable of running 3 separate zones. Others, that are less costly, can run 2 zones.

Good luck .

 

[zieglj01]

For front ported speakers up front (do not recommend rear ported) - I would still
think about the Focal Aria 906 - and they do get nice reviews and did measure
better than the B&W CM5 speakers.

However, your call

 

[jmasud]

Thanks for your feedback, guys. This is exactly what I came here for, and is extremely useful.

My quick responses to some of the points, which have raised additional questions in my neophyte mind, beginning with markw's comments:

"1) The rear channels will be going through two preamp stages. Not really a good thing."

Makes sense. The other vendor proposing Focal Aria speakers and Quad QMP mono amps was suggesting connecting the AVR directly to the power amp (i.e., no need for a separate preamp). This would seem to resolve the two preamp stage problem, and I suppose switching between HT and music inputs could be done directly through the AVR, with the same rear HT/front music role for the CM10s. Is this a workable and better solution, or would the music sound still suffer given presumably lower quality AVR preamp?

"2) For multi-channel, the volume levels are balanced relative to each other. When you change the volume level for the preamp, the multi-channel balance will be changed and will need to be rebalanced if you want to maintain the same balance.
3) The sources plugged into the 1570 will only play through the rear speakers. They will never play through the other speakers. You may wind up regretting this, particularly the BD player, which is multi0-channel by nature."

Will the above arrangement not also take care of these two issues, as the AVR would be controlling the output for everything now?

Regarding your comment about the small front speakers, my constraint is that I only have space for bookshelf types at the front, otherwise would have placed the CM10s there.

Would love to hear what solutions to this situation you would propose. Many thanks!

 

[jmasud]

Hi Swerd,

Thanks for your excellent inputs.

I take your point about the CM5 v CM6. I didn't notice the dB ratings, and automatically presumed that CM6 would be rated higher. So the only advantage to CM6 seems to be the top-mounted tweeter, which is supposed to give a better high frequency performance to the speaker? I guess for HT use that should not be a major consideration, and I could stick with the cheaper CM5 if it is otherwise identical (which would also allow me to place it horizontally, if that helps with the acoustics).

As for the space behind the bookshelf speakers, I would have at least a couple of inches, and maybe twice that above (i.e., between the top of the speaker, if placed vertically, and the bottom of the shelf above). I don't know how much that would affect the sound, considering these will primarily be used for HT and not for listening to music. This may also address the point about their 'harshness' at high volumes in 5.1 HT listening mode, as in they may not need to be turned up too far with other speakers also in use.

Would these compromises be potentially deal breaking in your opinion? I'm aware that I'm trying to make the best of a tricky situation, and am willing to pay a small price for that, but not a huge one!

 

[jmasud]

One final point:

I'm still a bit confused why using the rear HT speakers as main music speakers should be so complicated. After all, the conventional configuration of using the fronts for both HT and music is not a problem, so switching the front and rear HT preouts on the AVR should essentially accomplish this without affecting the other connections for music sources. What am I missing here? How would the 'normal' configuration be wired with an AVR and external preamp/amp, if I've got it wrong in my head?

Sorry about dragging this out, but it's going to be a major purchase for me and I want to be sure I'm not experimenting with something completely untested here.

 

[Swerd]

Jmasud – Lot’s of questions. Your old Sony may have been one of those simpler “home theater in a box” sets, with very limited set up options. The answers to some of your questions will make more sense once you’ve gone through the set-up process with your own newer AVR.

I'm still a bit confused why using the rear HT speakers as main music speakers should be so complicated. After all, the conventional configuration of using the fronts for both HT and music is not a problem, so switching the front and rear HT preouts on the AVR should essentially accomplish this without affecting the other connections for music sources. What am I missing here? How would the 'normal' configuration be wired with an AVR and external preamp/amp, if I've got it wrong in my head?

It would be simple if your AVR allowed you the choice of doing that. No AVR I am familiar with does that. For example, my AVR allows me to play back music with the option of using, the front left & right channels, the front 3 channels, the 4 corners without the center, or all 5 channels. If I use a 2-channel stereo music source, the so-called all-channel stereo option on my AVR plays the left channel in the left front & left rear speakers, the right channel in both right front & rear speakers, and creates a left-right mix for the center speaker. There is no option of choosing only the rear channel speakers.

If suppose if I used my AVR only as a preamp and had external amplification for all 5 channels, and, if I could switch off the amps for the front 3 channels, then I could hear only the rear channels. It might not be an elegant solution, but it could work. That would allow you the choice and control of having all sound sources connected to one and only one preamp, the AVR, and avoid the complexity and cost of an extra stereo preamp.

To do this would require at least two different external amps, one to run the front 3 speakers, and one to run the rear 2. It might also save you some money to buy a less powerful AVR than the top-of-the-line Denon X7200W because you will not be using it's more potent power amp section. I believe, but I'm not certain, the Denon AVR-X4000 (or is it the 4100?) is the lowest price AVR that includes preamp outlet jacks for all channels.

There may be a more elegant and useful solution in the owner's manual for the AVR you are considering. You are going to have to do some homework and understand its 2-zone abilities.

I would not worry at all about the difference in sound quality between a good quality AVR and a 2-channel only preamp. I believe that was suggested by a salesman who is eager to make a larger commission.

 

[Swerd]

I take your point about the CM5 v CM6. I didn't notice the dB ratings, and automatically presumed that CM6 would be rated higher. So the only advantage to CM6 seems to be the top-mounted tweeter, which is supposed to give a better high frequency performance to the speaker? I guess for HT use that should not be a major consideration, and I could stick with the cheaper CM5 if it is otherwise identical (which would also allow me to place it horizontally, if that helps with the acoustics).

With regard to CM5 vs. CM6 question. I see no advantage from the top-mounted tweeter in the CM6. It probably costs more to make, and the B&W marketing people can advertise it as a highly visible “tweak”, but I seriously doubt if a top-mounted tweeter creates a major audible difference. In your situation, placing a CM6 in a bookshelf, might probably negate any small acoustic advantages a top-mounted tweeter might create.

As for the space behind the bookshelf speakers, I would have at least a couple of inches, and maybe twice that above (i.e., between the top of the speaker, if placed vertically, and the bottom of the shelf above). I don't know how much that would affect the sound, considering these will primarily be used for HT and not for listening to music. This may also address the point about their 'harshness' at high volumes in 5.1 HT listening mode, as in they may not need to be turned up too far with other speakers also in use.

Would these compromises be potentially deal breaking in your opinion? I'm aware that I'm trying to make the best of a tricky situation, and am willing to pay a small price for that, but not a huge one!

I think the limited space above and behind any small bookshelf speaker is small enough that you should avoid getting speakers with rear mounted vents. These vents are designed to augment the lower end of a vented speaker’s bass response. Blocking them is not good, and should be avoided. You will be using a subwoofer for bass anyway.

You asked about the B&W high frequency harshness. It is independent of low-end bass, and can be heard regardless of where they are placed. There is no “fix” for this problem, other than to completely redesign the crossover for these speakers. That’s for B&W to do, not you. For me, their high price makes this problem a deal breaker. However, you’re buying speakers, not me, so my opinion matters less. For what its worth, the much more expensive B&W 800 series speakers (that I've heard) do not seem to suffer from the harshness problem. The CM series is already high priced, and I don't recommend the 800s because their price is even higher. If such a price is an option for you, there are better speaker choices available.

Instead of vented speakers, I believe you should consider speakers that come in sealed cabinets – they're designed with no bass vent at all. A very good example is NHT http://www.nhthifi.com/Bookshelf-Speakers. They are well known for their neutral and uncolored sound, and in my experience, they don't suffer from any major flaws. They might make a good choice for your front 3 speakers, leaving you free to use floor standing speakers of your choice to use both as rear channel speakers in the HT system, and as a stereo pair for 2-channel music.

Are you in the USA? These speakers are sold internet direct in this country, but in other countries, I'm not sure how they are distributed.

 

[jmasud]

Thanks, Swerd. I've learned so much from you already!

I will check out the AVR manual carefully, as you suggest. I was primarily interested in the Denon X7200W because of HDMI 2.0/HDCP 2.2, Dolby Atmos, etc., but could go for less expensive ones if similarly updated ones become available soon, as I do want to future-proof for 4k (regardless of its worth, given that I am splurging on a total A/V upgrade). I'm told Rotel may not be coming out with their new AVR for at least another nine months, but am sure a cheaper Denon unit will soon follow.

As for the speakers, I'm really buying them blindly based largely on reputation, build quality, and, admittedly, aesthetics. I don't have too many options available locally, and have so far looked at B&W, Focal, and Martin Logan only (auditioned a few), and was sold on the B&W on all three counts. The similar Aria 948 and the Motion 60XT can't match the CM10 in looks or build, in my opinion. Haven't explored KEF yet, and maybe I should. My system requirements are not too high end, as the room serves as my general purpose living room/study/home office/casual entertainment area, and the acoustics may not be optimal enough to warrant a bigger investment (even if I could spare the extra cash!). So I'm basically looking for a decent HT upgrade to the puny outdated Sony 5.1 system to complement a new 65" 4k TV that is great looking to boot, and one that has impressive audio capabilities that can provide years of listening pleasure. Your points about the CM6 make a lot of sense, and I will try to look for sealed bookshelf speakers instead.

Finally, discarding the external preamp and connecting the AVR preamp directly to a pair of Quad QMPs is exactly what the other salesperson had also recommended. If that works, I'll only be left to choose between the Quad and the Rotel (or Anthem) amp. Any suggestions?

 

[Swerd]

While the Quad, Rotel, or Anthem amps will be good, because they are sold by local dealers, their prices will be high. It's safe to assume dealer's markup is about half of the price you'll pay, making dealer markup equal to what the dealer paid the wholesale distributor. Dealer service and information is certainly worth something, but I still don't want to pay their prices. That's why internet direct sales in general have taken off, and why small local stores have been disappearing.

I can understand why you want to listen to speakers before buying, but when it comes to amplifiers, I see no reason why the same thinking should apply. A well-designed and well-made amp with enough power to drive your speakers and to have some reserve power left over should not color the sound of your speakers. I would avoid buying from any dealer who claims otherwise.

I can recommend three excellent makes of amplifiers, all made in the USA, that are available to buy online. All are reputable companies, one is large and two are small, and I've actually witnessed their products in operation. I don't own them, but I do know other people, whose opinions I trust, who do own them. You might find ATI in a local audio store, but the other two makes are sold internet direct only.

Audio by Van Alstine (AVA)

AVA Synergy 240/3 3-channel $1599
AVA Synergy 300 2-channel $1499
Total $3098​

ATI (see Classic Audio Parts for online sale)

AT1803 3-channel $1500
AT1802 2-channel $1121
Total $2621​

Odyssey

Stratos HT-3 3-channel $1650
Stratos Stereo 2-channel $1375
Total $3025
​

AVA & Odyssey prices are for new amps sold directly from the manufacturers with their standard warranty and return policies. ATI prices from Classic Audio Parts are for factory B-stock models that are fully functional, but have minor cosmetic flaws. They come with ATI’s standard 7-year warranty.

 

[jmasud]

Thanks again, Swerd.

Apart from brands and prices, what power rating on the amp would you recommend? The CM10 (8Ω, minimum 3.1Ω) is rated at "30W - 300W into 8Ω on unclipped programme" which I assume is its 'program', and not 'rms' rating. I'm told the amp's rms power should not be more than half of the speaker's program rating, so 150 W per channel should be about right. Is that correct, and would, for instance, both the Rotel (200W/ch) and the Quad (260W/ch) essentially be too big and potentially damage the speakers? On the other hand, I've read reviews of the CM10 where it's been driven by a Halo A31 (250W/ch into 8Ω), so maybe the 300W rating is rms after all. Am confused!

 

[Swerd]

Apart from brands and prices, what power rating on the amp would you recommend? The CM10 (8Ω, minimum 3.1Ω) is rated at "30W - 300W into 8Ω on unclipped programme".

I'm told the amp's rms power should not be more than half of the speaker's program rating, so 150 W per channel should be about right. Is that correct, and would, for instance, both the Rotel (200W/ch) and the Quad (260W/ch) essentially be too big and potentially damage the speakers? On the other hand, I've read reviews of the CM10 where it's been driven by a Halo A31 (250W/ch into 8Ω), so maybe the 300W rating is rms after all. Am confused!

Limiting an amp's RMS power to no more than half a speaker's rating, is too broad a generalization to be meaningful. Ignore it. There is no standard in how a manufacturer reports a speaker's power requirements. Some makers give, as an upper power limit, an amp power that would cause thermal failure (a melted voice coil) of the speaker. And others report a range that reflects their opinion on what provides "adequate" performance. In what size room? And with what listener preferences?

In general, B&W speakers have the reputation of being hard to drive, and they seem to do well with powerful amps. So I wouldn't shy away from high power, in the range of 200 to 250 watts rated by the RMS method (see below). Of course, this means exercising some judgement and common sense by the user. If a speaker sounds like it's in distress while playing it loud, turn it down before damage occurs.

From a review of the CM10 in Sound & Vision:
"The –3-dB point is at 49 Hz, and the –6-dB point is at 37 Hz. Impedance reaches a minimum of 3.72 ohms at 115 Hz and a phase angle of –69° at 69 Hz."
http://www.soundandvision.com/content/bowers-wilkins-cm10-loudspeaker-test-bench
From that statement, I'd say the CM10 becomes hard to drive in the bass range around 115 Hz. It will probably benefit from more than 150 watts. And it will need an amp which is stable below 4 ohms impedance, as are most decent quality stand alone amps. B&W's claim of no lower than 30 watts and no more than 300 watts, makes sense. I'd go for the higher end of that power range.

From a review of the CM6:
"The speaker's moderately low sensitivity combined with a low minimum impedance means you need to carefully select your amplification."
http://hometheaterreview.com/bowers-wilkins-cm6-s2-bookshelf-speakers-reviewed/
The same seems to be the case for the CM6, and I assume for the CM5 with a similar or identical woofer. 200 watts is a reasonable upper range for the CM5 or 6.

I'm not sure what the British mean by "an unclipped programme". I assume it means properly recorded music, where the recording gain was not raised so high that the loudest peaks are beyond the recording equipment's capability.

A word about RMS power rating… It is defined, according the US Federal Trade Commission, to be an amp's highest sustained power measured over a continuous 5 minute period, while driving an 8 ohm load, over the full 20 to 20,000 Hz audio range, with a defined level of harmonic distortion, such as less than 0.1%. Most speakers, including B&W, require very low power (about 1 or 2 watts RMS) to produce adequate loudness for normal listening. But all music has brief passages that require much higher power over very short time periods. A good example, common in popular music, is a single short snare drum beat, a "rim shot". They are very brief, so they don't show up in a continuous 5 minute power estimate. But these brief loud transient sounds can easily drive a moderately powered amp (~100 watts or less) beyond its power capability, resulting in whats known as a clipped signal. Any amount of clipping is undesirable, and that's why people go for those big amps.

 

[jmasud]

Thanks, Swerd. You've been a big help. Much appreciated advice!