2 Channel: Klipsch Cornwall III, McIntosh C2500 pre-amp, MEN220 Room Perfect, MC2000 amp fed by Oppo BDP-105D and FLAC from Qnap NAS.
HT: McIntosh MX151 controller > MC 8207 amp with Oppo BD-105D, DirecTv DVR and OTA reception as sources and Klipsch Cornwall III. Zones 2 & 3 are AppleTV and 1 terabyte of AIFF music on external drive into the Oppo feeding Emo Mini X-100s. Dual PSA VS30SE subs
I specifically recommend against a tube pre-preamplifier. Why? The signals are so low a voltage that any (ANY) noise in the tube circuitry is amplified way out of proportion. Tube microphonics? Thermal noise? Hum? they ALL get amplified (really, really amplified) at that level. Once you're up above the millivolt range for the audio signal, the tube noise is lower in the noise floor.
For that reason, I prefer in order:
Passive devices (AKA the Sony HA-T10 transformers or other similar devices) Quiet solid-state step-up devices (nicest I ever heard was my Mark Levinson) Built-in MC inputs for the preamplifier
If it's tube sound you're after, go with an all-tube preamplifier or a tube buffer. Tubes are great for some things, but low-low voltage signal amplification isn't one of them.
Now that said, others DO disagree, and manufacturers DO make MC tube step-up devices. So read the caveat in my signature carefully!