Has anyone mixed SS and tube amps in one system?

Lots of folks do this but at a minimum you have to deal with differing input sensitivities in the amps. If they don't match you'll have to figure out how to match them (easiest way is with in line attenuators). Depending on the built in crossovers in your speakers you might benefit by using an electronic crossover (the best way to solve gain problems as well) but good ones are expensive. Personally, I'd just find a powerful tube amp to control the entire spectrum. You might be surprised at what 200 tube watts (+/-) can sound like.

I used a combo transistor and tube with best success on Vandersteen 4 A speakers. This was years ago, when Steve McCormack was modifying the Quad transistor "current dumping" stereo amps into mono blocs. I used one Quad per channel with dual Vandersteen outboard crossovers and ran Counterpoint SA 4 OTL tube mono blocks on the top.

Oddly enough, years later Vandersteen offers the model 5, which has a high powered mono transistor amp built in to drive the subs, and many users drive the top with Wolcott or other suitable tube amps.

Time marches forward and full circle.

Thanks for the responses! I'm not sure about the Vandy 4A's specifically, but it seems that I recall the Vandy's being somewhat inefficient, as are my 10t's. I suppose I came upon this configuration idea as a way to help insure that I could feed them all the current they might want via the transistor amps and let the tubes provide the magic. I've not yet used tubes, but I get the impression that most of tube amps with enough power to handle an inefficient speaker will either require more maintenance than I care to get involved with or simply cost too much for my budget. BTW, my 980's have an input sensitivity/impedance of 1V/33kohms. I don't know how this compares to most tube amps as I have not studied them intensively yet, however this does not seem to be unusual.