I've tried powering a Jolida JD100 tube CD and a Meridian 506 CD, both of which are respectable CD players, directly to my solid state amp that had volume controls for each channel. They both sounded flat to me. Uninvolving. After placing my Conrad Johnson PV5 preamp between the CD player and solid state amp, it made a world of difference IMHO, not just to my ears, but for every single person who listened to my system. It was just MUCH more musical and involving. I guess it depends on the equipment and maybe the music you listen to, since I've hooked both CD players up to a Conrad Johnson CAV-50 integrated and though that too sounds much better than the solid state without the CJ preamp, it doesn't quite have the same sound I prefer compared to the solid state mated to the CJ PV5. Definitely more slam and low end power with the latter. I've never had a truly high end solid state preamp, so I can not comment how that would influence the sound from the solid state amp connected to the CD player.
