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.

Thanks.