Opened up my VP-530 today. The ADC-to-USB is on a small, separate PCB that appears to be made by a company called Soundcorp. On the bottom of this board is the Burr-Brown PCM2901EG.
As for the Op-Amp's, there are 4 that could be potentially replaced. There's a guy that did this to the VP-129 found here
As for the Op-Amp's, there are 4 that could be potentially replaced. There's a guy that did this to the VP-129 found here