The only one I've heard of who has done this is a banned member, so all his threads and replies are erased. He replaced one of the OPA2134's with a LM4562 and the other with LT1364. He was very pleased with the result. Personally I can't understand why such an opamp as 2134 is used in an amp with this potential. OPA2134 sounds muddy and coarse, has a boomy bass and a very narrow sound stage (almost like mono compared to the better Analog or National opamps for examle).
If your friend is good with a soldering iron and comfortable with soldering and desoldering SMD parts, then go for one of the better opamps like AD8620, AD8066, LM4562 (=LME49720) or whatever you find promising. There is AD8599 which seems to be good, but there are not so many reviews of it yet. Soon? there will be OPA2827 from Texas. There are many threads with opamp recommendations. Do some searching. If you mod your amp, please post a thread here.
Why all these bannings, It's like a witch-hunt.
