Integrated Tube Amp vs adding a Passive Preamp

I'm considering an integrated tube amplifier (likely a Rogue Tempest Magnum or Conrad Johnson CAV-50) and would love opinions of what you'd recommend in the sub $2000 range (used). I'm open to other options than the Rogue or CJ.

I'm currently using a Rogue Magnum 88 amplifier, direct connected from an AH! Njoe Tjoeb 4000 CD, and playing through ACI's Jaguar 2000 monitors with a pair of ACI Titan II subs. I've been extremely pleased with the sound, but am limited in terms of volume control to the digital volume on the CD player. There are two issues: 1) I can't play music as quietly as I'd like even on the minimum output from the CD and, 2) I'm concerned that using a digital volume control is likely degrading the sound quality when it is played at low settings (1-2 out of 20).

I'd like to keep the system as simple as possible, hence my interest in integrateds. I'm also considering a passive preamp added to the Rogue Magnum 88. The two lead options I'm considering, if I go that route are the Channel Island Audio passive pre or one from Reference Line (although I don't need all the inputs).

I'd appreciate any comparisons of the Rogue Tempest to the CAV-50 - plus any other integrated tube recommendations. I'd also like thoughts on the likely impact of using the digital volume control on the CD and passive preamp options to add an analog volume control to my existing amp.

If you don't need a remote with a passive pre, and want the purest and most bang for the buck, check out the EVS ultimate attenuators.
Good luck.
HEre's what you need to do...Change as little variables as possible, first of all! If you change too many things at once, you won't know what you have/had!
I would pick up a passive preamp and try it(although it's not any different mostly than your CD player connected directly to your amp currently. Then you should try a very good active preamp as a comparison! You'll likely find the best one's of those in the "tube preamp" genre.
Bottom line, people can tell you all the feedback you want to hear, but you still won't know until you try experimenting With YOUR SYSTEM SETUP! You can always sell what you don't use later.
You can pick up passives that are exceptably transparent in the $400-500 range used (like McCormmack TLC, Pass Aleph L), and tube pre's (like Audio Research LS2/5/7/15, or better) for $500-700 range and up. Other tube options are Cary's older $1200 non-remote line preamp used at $600+(simply superb), Copelands $2k pre used at $1k range, etc.
good luck
Myraj - Thanks for the lead on EVS, I'll check it out.

Exertfluffer - I agree with changing one thing at a time to hear the difference. I'm trying to keep it simple, but and active preamp could be worth a listen too. I'll look into the passive and active pre amps you mentioned.

I guess I have a nagging question of is the rogue the best value for the money. It is a huge improvement over the mass systems I was listening to, but I have no experience with other tubed gear. I had a CJ-2250 that was built great and sounded nearly as good as the rogue, but lacked some of the "liveness" that I got on vocals and live recordings with the rogue. Any opinions on other tube integrateds or amps vs the rogue would still be appreciated. Thanks for the help.