I have a CD80 from '91. It's definitely at 16bit 4x unit with the single beam CMD-1 transport. It absolutely killed the other CD players kicking around at the time. McCormick used the unit for their first post Mod-Squad CD player (they just tweaked it up and put their own frame around the face). Somewhere around 96 I started having drop outs with the direct-circuit-board-mounted analog RCAs and decided to upgrade to an outboard transport. I initially used a PS-Audio Ultralink which sounded so good in combination I started to pull away from my records (I have a killer analog rig with ET2 arm and Roksan Xerxes deck - so that's saying something). I upgraded that setup with the Audio Alchemy DTI Pro which really smoothed things out. Later on I upgraded the DAC to a Muse Model 2. Digital cables were Van Den Hul D102 Mark III, "The First", and later, Silver Serpents, Illuminati Orchid, and Cardas Lightning. (Rest of system is ProAc Response 2, Acoustic Research SP14 & Classic 60, MIT wire, later Tara RSC, later Zu Cable.) The CD80's strengths - slamming bass, vivid midrange timbre, excellent soundstaging - came through great when used as a transport. The EAD7000 is a kickin DAC so should sound great with the CD80, Daveyf. I initially compared the CD80 as a transport with the Optimus CD3400 and much preferred the CD80. Recently I compared it with a '97 vintage Theta Data Basic II. The Theta improved on the CD80 in several important ways that reveal both the strenths and weaknesses of the CD80 as a transport (keep in mind the Theta cost almost 3 times the CD80, almost a decade later, although I purchased my CD80 as a closeout for $500 in '92, and got the Theta used for $550). The Theta has the slamming bass and vivid midrange, but has a smoother treble, with no audible digital artifacts. There is greater cohesiveness, the music feels more "all of one piece" - with greater overall smoothness. The soundstaging is about the same on both (i.e. HUGE). The CD80 has a bit more boogie factor, especially on Rock, Rockabilly etc... Actually, the Muse moved things in smoother direction, so going back to the CD80/PS Audio Ultralink combo gives the maximum boogie and it a killer rig on rock. I wasn't really aware of the digital artifact issue until I got the Theta. It's pretty subtle - but up in the mid to high treble, there is some transient digital glaze to the CD80, audible when using the CD80's built-in DAC and to a lesser extent with the outboard DACs. That little edge was pretty easy to live with all those years, it's amazing how well the CD80 has held up. As for tweaks, heavy and solid as the CD80 is, good feet or bladder platform is a must. I could dramatically hear the difference between sorbothane pucks and Black Diamond Racing Cones (it likes the cones). I also used Mod Squad combo sorbothane, aluminum short cones for a long time. The Audio Alchemy DTI Pro (or kin) unit is a must too. It has a dramatic and positive effect. The EAD 7000 unit has a "digital flywheel" (same concept) built-in so you might not miss it. These DTI units are cheap on the used market. All in all, the CD80 is a great transport, and with a DTI and an Ultralink makes such a good rock rig that I haven't sold this gear even though the Theta, AA, Muse Model 2 rig bests in in many areas. I heard that back in the early 90s it was popular to put a tube output stage into these. Anyone do that mod?
Anyway - the CD80 is highly recommended too!