I use a PS Audio Statement Extreme power cord on my scd-1 and feel it provides a blacker back ground; not a revelation but certainly worth doing. Not anywhere near the inprovement that the clock and other mods have made. I have used passive power conditioning in the past (not active, couldn't justify the price) and felt it put a veil over my speakers. I disconnected the unit and go straight into the wall. These are my experiences others may experience something different.
Chuck
Chuck