I am familiar with the card, and some of the suggestions. There have been some changes in what we have to choose from. The original LM4562 are actually a fairly decent performer, but I'm not a fan of the JRC. The real issue is what is available in DIP format. The LM4562 (original) and the LME49720 (your replacement) are actually the same die. If you do choose to replace the OPA-2107 with the OPA-1612, you really do need it to be as close to the board as possible. So if you mount it on an adapter board and settle on it, I would remove the socket and place the adapter directly into the board to get it as close to the ground plane as possible.