By the way, in regard to original question, it is very unlikely that AD8620 sounds any different than AD8610 - as long as only one opamp is used. If you use both - which is the only sane thing to do - you will get some crosstalk, getting higher as frequency goes up. Depending on opamp, application, board layout, decoupling and voltage regulation, this might or might not be audible. I think what Morsel said is that with META42, difference is inaudible. It is possible however that in a different environment such as dual mono configuration or even separate voltage regulation per channel this would be audible. I think ppl tried it in his amp and found no difference though.