The op-amps were the last of several sections that were upgraded in a Adcom GDA-600 DAC from a thread in DIY online. Listening was done after each section , power supply upgrade , caps around op-amps, the op-amp change and lastly the reserve caps at pin 4 to 8, each with SS-Audio discrete op-amp making the most positive improvement in sound, the sound is more open with a large soundstage , best and my peeve with digital is piano, the higher octave and flats are more real, to life I like that a lot.

Thomas S.