Sorry if I wasn't clear on my thoughts. My statement is certainly subjective to several factors. I'm speaking in very general terms. Let's say you have a decent sounding receiver with internal amplification (OP's Denon in this case). And let's say you just added some rocking new speakers that demand some juice. Your cables, interconnects, transport, etc. are all of decent quality. You now notice that when watching movies or cranking the music in your somewhat large living room, that your new speakers sound a bit weak on the bass and maybe a bit strained at upper volume passages. It's just not 'crisp' I guess is the best way to put it and you're hearing a lot of the speaker along with the sound coming out of it.
Generally, and I want to stress 'generally', that would indicate the amplifier is not outputting enough current to adequately maintain the drivers in a linear motion during peak moments, and the amplifier does not have enough reserve capacity to deal with heavy / fast bass transitions (rapid 50 cal gun fire, cannons, explosions, etc), or, loud very full vocal passages containing a wide dynamic range (opera etc).
In order to fit a 7 ch amp inside a compact receiver, the manufacturer will have to do away with things like large capacitors, separate power supplies, and large toroidal transformers. Sure, you get the claimed "125wpc", but is that rated as sustainable from 20hz to 20khz on all channels at once, two channels at once? Is there enough juice and reserve capacity behind the rated wattage to adequately drive all output channels or even stereo channels simultaneously? I would have to say in most cases no, as these products are geared towards the entry level to mid level AV buyer. Buying a combo receiver/amp is a rite of passage for just about every seasoned AV enthusiast- It is a good an reasonably priced way to break into the world of fine sound and home theater. Ask anyone here who owns a stratospheric system and you'll get a "yes" that they owned a receiver / amp combo at one time.
This is where moving to a separate dedicated amplifier comes into play, as a quality amp will account for all of the above limiting factors and then some. Adding a separate amp is a good evolutionary next step and eventually the next purchase will be a quality dedicated processor. A well built 50wx2 dedicated stereo amplifier from say Mark Levinson, McIntosh, etc. will blow doors on a 200wpc rated chain store brand receiver in terms of sheer power and delivery of it to the speaker, constantly, across the full frequency range and across all connected output channels.
In this case yes, a dedicated Arcam amplifier will indeed out perform the internal Denon receiver amplifier section, *assuming* the attached speakers are of good quality and are capable of reproducing the increased difference in sustained power. If the speakers are not of good quality, they will distort and sound flabby regardless of what they are attached to- Essentially they will only output what is within the range of their capability.
Make sense?
