Chuck, I am well aware of the two parts. I happen to have a good stash of both lying around and use both and like both. I do NOT, however, notice "so much more detail" from either part. In a ONE PIECE low powered headphone amplifier, the potential benefits of one over the other are negligible. Have you done a double blind test with the two parts? Can you HONESTLY tell me that you can HEAR the difference between the two in the same application changing ONLY ONE PART??? If so, I would love to know the application! Please send me a schematic so that I too can share in that "so much better" application! I would be happy to whip it up on some protoboard and see the error of my ways!
If, however, you are telling me that you like the LM4562's in a signal processing board, or a multi-part system in which the signal passes through dozens of opamps, then maybe we would have an interesting discussion. I don't buy it that you can hear the difference in ONE PART.
The irony in my earlier suggestion to put a socket in and try different parts is that once you hit a certain threshold for decent opamps, they sound pretty much the same! The point of the socket isn't to find the best opamp, rather it is to prove to yourself that they don't make an appreciable difference!!!
But hey, there is ZERO harm in using a LM4562, so why the heck not if you think it will help. I think most of us can swing the extra $2.
PS Just to clarify, if somebody just WANTS to use a LM4562, there is no reason that they shouldn't! I have no problem with the part and think it is excellent, just for the record.