Part 1:

I asked ATI.

Their gist is this: yes, even order is reduced but odd order isn't. But a balanced amplifier design still also reduces any common mode noise introduced into the signal external to the amp itself that ends up on both legs inside the amp. So they say, 2 out of 3 sources of noise are reduced. They also added, which kind of makes the whole argument a little moot, that we are talking about a level of 0.003% distortion here and listening tests have shown that it can take upwards of 1% to be audible, so it certainly isn't true that leaving behind odd order vs even order at this level will make a component sound any worse. They do say that one of the reasons why they offer balanced amps is because other amp-makers do too, and that balanaced designs are commonly perceived as superior to single ended designs. So there is some marketing in there.

So I do have to admit, that hey, I learned something. I didn't know about the even vs odd order thing. One question though: my impression is then that you still have a choice. In most (if not all) fully balanced designs, you can still just use RCA connections to use half of each circuit, right? And even if you want to use balanced connections but not the balanced part of the amp (why not just buy a single ended design then...), I have seen those converter jack type things in pro catalogs. ??

Part 2 will be McIntosh.