Right, but those numbers you posted, all the technical caveats around them, are not how it comes across at face value. As someone who is used to home audio historically being rated at 8Ohms, the 4Ohm rating, just to make the power output seem like so much more, is misleading, at least to some. This is a new trend to me. I see a lot of amps using this now. 4ohm has always been the realm of car audio, 8ohm for equipment with mains power. Most of my speakers are 8ohm. The other misleading trend is to use combined channels, instead of per channel power rating. This makes for a lot of erroneous information to sift thru, comparatively.
I know it's easy for those who are all into the technicalities of these things to delve into all the particulars, but to me, it's misleading.
You are right, such specs are very confusing to inexperienced EEs if they are new in this hobby, let alone the average hobbyists.
When I see an amp rated at 300wpc/4ohm, my hopes are at least that it would be around half, into 8Ohms, which many amps are.
That is more than reasonable, but unfortunately, for those new generations of mini class D amps, it seems more realistic (those again, I agreed, not reasonable) to hope for that being the best case scenario (not "at least"), and it would be for at least 1% THD. In this particular case, Amir's measurements show the Fosi V3 could in fact claim
half of the 300 WPC 4 ohms, at 1% THD+N, with the 48 V PS.
So this mini amp is about as powerful as your SA-8500 for real world use.
What you are proposing, is information suited more for professionals and science minded people. Meanwhile, someone like me sees this:
If you say it's fine to use it turned all the way up, that will certainly help. I have been cautious to use it beyond 3/4. I have used it with 3 different preamps. To have to root around to find an ideal preamp to get the most out of this, starts to remove the bargain from this equation.
Yes you can absolutely turn the volume to maximum, for reasons I explained before.
As you know, your Pioneer integrated amp has the following feature:
That is, you can remove the jumpers and use it as a power amp. If you do that, the Pioneer will then behave just like you set the volume control dial to maximum and you will be controlling the output from the external device.
Just a reminder, on integrated amps, including this Pioneer, it is not advisable to max out the volume control, it will be harmful to both the amp and potentially the speakers especially certain tweeters because of the resulting distortions from clipping. I am talking about normal input level such as that from a CD player, tuner, Blue ray playe or turntable.
I have two vintage Pioneer amps/receiver. The SA-8500 I own, albeit integrated, goes noticeably louder without being maxed out using the same speakers. I know it is basically a 60 watt amp. I'm ok with a 60w amp, but in the same family of amps, or even across brands of similar types, 100watts has always been better. With my use, these numbers always worked with little variance of the volume control across brands with the same claims of performance. I could expect to not have to use more than half of the volume control range, or even roughly 5/8 if I was feeling extra rambunctious. That one rough measure is still the same. It hasn't changed, even with aged hearing. In other words, I could historically go buy just about any name brand, 100wpc/8ohm amp, and expect similar performance across the known brands.
Again, as explained before, don't pay too much attention to that, you cannot tell if one amp is more powerful than the other by the volume position you set it to, as it depends on at least two things:
1) The gain of the power amp.
2) The type of volume control used, for example, does the Pioneer use "linear" or "log".
So, you can have one amp that required you to turn the knob of amplifier A to 10 O'clock and amplifier B to 2 O'clock, and get the some SPL, but the amplifier B may actually be 2 times more powerful, just that you have to turn the knob up much higher.
Take a look, just an example, with regard to 2)
Potentiometer Taper | Resistor Types | Resistor Guide (eepower.com)
With regard to 1), I can use my Marantz vintage separate pair as example:
The amp has a "flat amp" feature, that results in a much lower gain, so when I use the feature, I have to have the volume pass the midpoint, otherwise, I could listen to the same level of loudness at about 1/4 or less on the volume. Yet the power amp is still the same 140 WPC into 8 Ohm rated.
Double the headroom with both amp and speakers, was always the sure bet to safely avoid distortion to where I never had to think about it again no matter what I played.
You are more sensible than me, I go with 10 times what I need if at all possible, but I won't go for less than 4 times.
Now it takes techies and outfits like ASR to get to the actual working nature of these things. How about they just use the actual values up front first and foremost, so I don't have to turn over a bunch of stones to get to the truth. If it's an 89W amp under the best possible circumstances, call it that. Otherwise the 300wpc claims are a stretch at best and now I have no confidence in these otherwise sketchy numbers.
I agree with you on this, the ASR gang discussed that, and some pointed out the fact that many manufacturers play that power/number game so in order to compete they all have to do it. Apparently even Texas Instrument had given them the green light to advertised as they (the manufacturers) see fit.
Like I said, I am not disappointed with the SQ, I just don't want to fry the thing prematurely trying to make it perform at it's limits from here on out. The Pioneers, which went for 25-30 years before needing a rebuild, was likely because it was used lightly with regard to it's available headroom, relative to it's duty.
You won't fry it with volume set to max., for reasons explained. That is, it is a really a power amplifier, fitted with a taper pot, that makes it controllable, but still a power amplifier. All power amps that don't have a passive volume control feature are effectively "maxed out" in volume.
