Hi Srafi,
The most important is to keep the amplifier from blowing up. :) Electrolytic caps have a lifespan of about 20-30 years, and when any of them goes it can take a lot more of the amp with it. If the transistors are no longer made this can effectively turn your amp into a brick.
I would leave this up to an experienced tech, but one recommendation may be to seek higher temperature caps than originally, within reason. The higher the cap temp, the longer the lifespan. I don't know what Krell used, they may have already used this trick. :) I think after 80 C is the 105C caps, usually. If that's already what is in that's probably good enough.
Otherwise, for sound quality, look for any AC coupling caps in the audio path, especially at the input. Those could probably be replaced. I like Cornell Dubelier for sound, inexpensive (RelativelY) and small size.
The most important is to keep the amplifier from blowing up. :) Electrolytic caps have a lifespan of about 20-30 years, and when any of them goes it can take a lot more of the amp with it. If the transistors are no longer made this can effectively turn your amp into a brick.
I would leave this up to an experienced tech, but one recommendation may be to seek higher temperature caps than originally, within reason. The higher the cap temp, the longer the lifespan. I don't know what Krell used, they may have already used this trick. :) I think after 80 C is the 105C caps, usually. If that's already what is in that's probably good enough.
Otherwise, for sound quality, look for any AC coupling caps in the audio path, especially at the input. Those could probably be replaced. I like Cornell Dubelier for sound, inexpensive (RelativelY) and small size.