Rob,
I don't know what speakers you're using but I would make the effort to hear them with the Quicksilver V4. If you're really happy with this match I'd be cautious about reversing to tube preamplifier and SS amplifier. If you find the V4 the sound you've been looking for, a SS amplifier will be hard pressed to Sound the same (even fronted by a tube preamp). They're not the same, I'd strongly recommend that you listen to both approaches and decide by simply trusting your ears. There's no substitute for actually listening when this is possible to do so. The speaker's design characteristics and load (ohms) will determine which type of amplifier is the better match for it. You have to listen and go with the one that moves you the most.
Charles,