3zub,
I'm a fan of tube pre-amps, but I would not necessarily suggest it for your setup. In a combo system, using bypass, the dedicated 2-channel pre-amp would be used any time the system is in use for either 2-channel music or HT. If you used your system for TV, you would have the tube pre-amp on a lot and decrease the lifespan of the tubes significantly.
Now, if you don't use the system that much, or if the cost of the tubes in the pre-amp doesn't bother you, go for it! Otherwise, consider a solid state design.
Enjoy,
TIC