What is the CDP you are using? For me I have used Tube buffers and various tube preamps as a buffer between my CDPs or DVD players and the results have been good to me.. The tube buffer I used was a Grant Fidelity DAC-09 with a Sony SCD 595 6 changer player. Currently in one system I use an XianSheng 728A preamp as a tube buffer getting signals from an Oppo DV908H. The difference with these budget players was good. Nothing earth shattering but different on some recordings. With the Grant Fidelity DAC-09 with an upgraded tube I had a REALLY sweet mid range and highs vs the stock Sony. With my Oppo and the 728A with Old stock Sylvania tubes and upgraded rectifier tubes the sound was clean and midrange too was sweet. When I had a PS1 going into an Aric Audio tube preamp all I got was extra fuzz and noise.
Which Decware preamp or buffer will you be using too? I also at one point had a Yaquin 6SN7 based tube buffer and it made the music blah sounding to me. I guess what I'm trying to say is tube buffers/preamps can add a different sonic flavor to your systems depending on the quality of them and you can have varying experiences.
2 Channel: Work in Progress...
HT: Oppo BDP-83, PS3->Outlaw Audio Model 990->Emotiva UPA-7->BJC 10 White