"Official" All amps sound the same thread

I thought I would try creating this thread to isolate this endless debate. Maybe we can even get it stickied.

The argument - All amps sound the same vs amps don't all sound the same

Some Key points -

* Receivers should be excluded from consideration when they are running in any proprietary processing modes and/or have room correction or other EQ active
* Clearly amps are imperfect so they ALL have distortion. And clearly this distortion does not have to be identical. The question is whether this distortion is audible or not.
* People don't define 'sound the same' in the same way so be aware of that when debating this topic. To some people 'sound the same' mean two amps cannot be differentiated in controlled and blind testing; to others, it means they listened to the two amps knowing which was which and could hear the difference.
* People clearly don't agree on the merits of blind testing and probably never will
* It's possible some amps do sound different because of their design. For example, supposedly SET amps have sufficient distortion to be audible. Or some manufacturers could have decided to roll off their high response for some reason etc. Obviously if a manufacturer was not making every effort to create an amplifier with a linear response, there's no guarantee it sounds like an amp which was.

Some Interesting Links

Here's a link to an article by Rodd Elliott about why amps could sound different. He's a circuit designer and seems to be a clear thinking objectivist, so I think his article has more merit than most I have read on this topic.

http://sound.westhost.com/amp-sound.htm

Here's are some links to Sterophile listening tests -

http://www.stereophile.com/features/587/index1.html
http://www.stereophile.com/features/113/

Here's a link to a Stereo Review listening test from 1988

http://bruce.coppola.name/audio/Amp_Sound.pdf

Here's a listening test comparing a low end to high end system (There's a whole thread discussing this one)

http://www.matrixhifi.com/ENG_marco.htm

Common Positions on the debate

Position 1 -

All amps sound the same when they are not clipping and are designed for a flat response

Position 2 -

Amps don't all sound the identical, but they are so similar in sound, even listeners who claim to have "golden ears" struggle to be able to compare two amps in controlled and blind testing. They are sufficiently close in sound that there's little reason to choose one amp over another based on sonic character.

Position 3 -

Amps may sound very similar, but there are important differences. They sound different enough that it's worth one's time to demo amps, read reviews or otherwise attempt to make their buying decision based on amp sound.

Position 4 -

Amps can sound obviously different, and if you can't tell the difference, your equipment is lacking or your ears are lacking

For the record, I think amps could sound different. After all, they are imperfect, thus must have distortion, thus could sound different.

However, most manufacturers seem to be trying to make amps with limited distortion. And they are pretty good at it with THD+N figures below %1. Some claim that's inaudible distortion.

I personally think that amps could have subtle differences due to their distortion, but they are insufficient to tell in AB testing. I base that on some listening tests done by supposedly 'golden eared' audiophiles who could not tell one amp from another.

Two amps should not sound dramatically different unless one of them was poorly designed because once again, the usual goal is to make amps that do nothing but increase the amplitude of the signal.

Position 1 is almost an exact quotation from a number of regular posters.

Can the dynamics be limited when clipping is not occuring?

What I gather, from reading from some HK fans, is that they feel HK is better overall, but I am certainly making a guess as to what they mean.

As to why that would be, I could not say. Nor does it make sense to tell people they are wrong.

But it should be noted, that nn many cases people are doing sighted testing at separate moments in time. Many consider this unreliable.

Also, receivers have more circuitry than just the power amps. You have digital to analog conversion, volume control chips, and other misclleaneous circuits. Can those impact the sound? I don't know.