I have been enjoying my Adcom GDA-600 DAC for several months now, but I can't help wondering if it could be updated or modded to improve the sound even further. The original design of the unit appears to date back to 1993. In my mind, the obvious place to start would be to look at the analog output circuits for easy upgrade, such as replacing capacitors. I don't have enough of a clue about electronics in general, and especially about digital electronics to know what changes might be realistic and/or would yeild any audible improvements. I have a schematic of the unit attached... it would be interesting to get input from some of the more electronics savvy folks about what improvements might be realized. Of the 5 pages, I suspect the power supply section on page 1, and the analog output section on page 5 would be of most interest from a hobbyist or DIY perspective. I don't imagine there would be much value in messing around in the digital sections.