I'd like to offer another point of view, and suggest that
your plan to modify the Adcom GTP-750, and maybe the 5802, is not well considered. I've been an audiophile for 40 some years, and have built my own gear from kits, and also done mod's (such as the DIY version of Musical Concepts mods for the Hafler 110 preamp and the 220 amp). I have yet to find a mod that is an improvement over the original product. Think about this: if a different circuit, power supply, etc., provided better sound and was cost effective, why didn't the manufacturer simply design it that way from the beginning? Mods are rarely cost effective -- a lot of money for minimal difference. Infact, I would almost suggest that mods are rarely better, simply different. If what you want is a different sound, then I recommend selling the preamp, amp, etc., that you have and buy something else. Finally, once you modify a unit you have effectively reduced its value to other potential buyers, and voided the manufacturer's warranty. My best intentioned advice here is to rethink mods to your Adcom gear. Both units have gotten very favorable reviews/ratings from several high-end audio mags, so I doubt you will improve on the sound by "modding" them.