I probably am the only one who feel the way the question is asked, the only right/logical answer is "Yes" so there really is no point voting. That's absolutely just my own opinion/logic.
I went to a local dealership for one of their "Tech Talk" nights and that evening, they had Len Feldman, from Audio Magazine. The topic of the night was the same as this thread and he was from the "if two amplifiers of similar power output and specs are compared when the output level is the same, they'll sound the same" camp. I didn't work for a high-end dealer and to those of us who worked together and were there that night, it was like blasphemy- we were a Sony/Pioneer dealer and part of the Sony line we had was their VFet amps- they tended to sound more like tubes than transistors and not at all like the "common" variety of amplifiers (not receivers- this type of transistor was only available in integrated amps and separates). We were amazed that someone with his background would say this, being in our 20s and so sure of everything that we really didn't know very much about, but that never stopped us.
It took a while, but Feldman eventually admitted that he could hear the differences and that his test methods didn't allow enough characteristics to show.
FWIW, I have thought of Sony's better amps, like the old Audio Lab/Esoteric and ES lines, sounded very smooth and neutral to warm with their lower priced receivers and integrateds sounding fairly similar to many other brands. Their better receivers tended to sound beefier and smoother than a lot of other brands' offerings, too. Pioneer's lower line, even into the upper-mid line, sounded decent but unspectacular. Some of these are selling for big bucks now and I don't understand why- they weren't special then and they aren't special now. Onkyo was solid but we didn't carry them when I was working there and I haven't had a lot of exposure to theirs. Yamaha always seemed a bit thin-sounding, to me. FF to now and I'm using a Denon AVR-2313CI for everything but I don't have a 5.1/7.1 system- I'm into audio, not video and surround. The cost to do it right would be very high, for me. I built my speakers a while back and they do very nicely WRT extended frequency range. The impedance curve isn't particularly flat, but the receiver does a great job in the low end- smooth and very deep. It has pretty good cajones, IMO. I'll be able to compare it with a Parasound A23 soon- it's supposed to be here on Tuesday, but I think that will have better dynamics and impact. However, from the standpoint of listening to music as the main activity, this AVR sounds very good. I admit that this could be the result of a series of happy accidents, but if I feel the bass from dual 6-1/2" woofers, without a subwoofer or low frequency EQ and my feet off of the floor, I have to say it has some balls.