just to share this info, palagi kong nakakalimutan kasi. last month, i found a universal remote that could control practically all my surplus CDPs - volume and track selection. it's China-made, URC-900, costing P120 and available in many shops here in Davao. it could store memories for 10 remote codes, including TVs and VCRs. anyway, just one unit controls four surplus CDPs in my room - Sony X333ES, Sony 502ES, Onkyo Integra C 901XD and Kenwood DP-3300. it won't work on my Revox, however.
if you want to control CDP volume, all you have to do is use the variable output RCA jack at the back of the CDP (to amp) instead of the fixed output. for those without variable output jacks, only the track selection would work. i've been using it for about a month now and it's been reliable so far. bought two other units of this remote: one for another set of surplus CDPs in my living room, and another as reserve, sakaling magka-ubusan.