It is the rarer way to go, but it is done. I myself am running an InnerSound SS preamp into my VTL MB-185 Sig's. I just got tired of trying to find quiet tubes for the high-gain sections in the preamp. In my experience, the tubes make the most difference to the sound when they are driving the speakers anyway. I think many folks do the reverse, with tube preamplification and SS power amplification, because they actually do not want a real 'tube' sound (or tube heat, or replacement costs), but would like to have a bit of tubularity in the mix somewhere, if just to feel they are being a true audiophile by running some tubes.
Replacing an all-tube Conrad-Johnson PV-8 in my system, the SS preamp has given me better transparency and definition. The old pre had a slightly less clear soundstage, with image outlines that were not as sharp, and a less-neutral warmish tonal coloration. Dynamics are now more unfettered, and the bass has gained control and speed. I do not hear increased grain, but maybe just a little hardness, since the tube pre was comparitively softer. I think the new preamp is more accurate, and passes the cleaner signal. I loved my C-J when I used it before, but when I drop it back in the system now, I am aware of losing some clarity, bandwidth, impact, and immediacy.
But to be fair, the InnerSound is 10 years newer than the C-J, and twice the price. Aspects such as the attenuation control system are completely differently implemented. And when the C-J originally replaced an even older SS preamp several years ago, I heard many of the same improvements then that I'm talking about now, so it's all a matter of the individual pieces in question. I have no doubt that newer, more premium tube preamp designs would've also improved on my PV-8 in many of the same ways, but there still would have been the matter of finding good tubes.
I have done the same thing for my phono preamplification as well, hearing a lot of the same improvements and more, moving from the C-J's built-in phonostage to a SS Camelot Tech Lancelot unit. Here the benefits from not having to find quiet tubes are even more profound, and the sound only got better. But again, the C-J was the only tubed unit I have owned in preamplification, and better surely exists. One thing, though - if I ever go back to tubes in these stages, it will be with designs that employ lower gain, so the tubes won't drive me batty. For the time being, however, I remain firmly tubed in power amplification.