Technically any class amp that is fundamentally sound and well built will sound more or less the same at any volume and power level within operational specs. Also, well designed amplifiers aren't made specifically for any impedance load, they are merely rated for certain impedance loads because at too low of an impedance they won't deliver enough current and they may clip, shut down, or explode depending on the build quality.
Class A is nice, but at low volumes I don't notice any difference to a well designed class A/B. Besides, many class A/B amps will operate into class A at really low power anyways.
Do you know what class A means?
At VERY VERY low volumes there might not be any difference since you can barely hear anyway. But I think at about -35 to a 0 there are clear differences as far as what I've read from different amp owners.
From what I've read, a owner of klipsch said there was a BIG BIG difference in sound moving from a Denon 7.1 reciever to the GLOW Amp One. What happnened was his friend left him the glow amp one because he left the country, and this guy had it in his closet for a year before trying t out... one day he was bored and tried it out and was "wowed". He said it addeded dynamics, bass, and clarity to a big degree.
From what I read from many owners switching from Denons and pioneers to a A-class amp, in the simplest form, the sounds from the speakers sound more lifelike and bigger in size, more presence.
So when a T-Rex roars in jurrasaic park, you would actually hear a REAL LIFE-like dino roar in life size scale.
One guy said he freaked out because when he was listening to Johnny cash on his GLOW Amp One (A-class) in the earky morning played through his AM Radio he thought he was hallucinating because that sh!t was 3d and he thought Johnny Cash was in his room so he immediately turned it off because he got scared lol..
There are so many shitty sounding recievers out there now that just pack it up in 7.1 with total **** components because the HIFI crowd goes with matrix code to listen to movies anyway. But for 2.1 analog listening to movies and music, I think amps and cables are pretty critical.
Suppose one gets a DAC to decompress the digital mixes to analog for neutral and pure sound, amps get even more critical.
The above makes sense, but what you said also makes sense since 5.1 reciever would digitize and matrix that sh!t to a heavy degree. So in the end, it all sounds the same.( whichever reciever or whichever cable) but for those who want a purer and a more neutral sound from the source (way it was intended) amp and cables can make a diffence I think in analog mode..
Then do the digital mixes sound better than analog? Many if not all audiophilles would agree analog will always sound better to a heavy degree.
If you dont have the budget and dont have the time nor the interest in sound to an audiophille degree somewhat, the hifi market 7.1 recievers with a HTIB will do.