Larry, I've owned Sound Lab U-1s for about four years. Before that, I had Quad ESLs (57s), Acoustat 2+2s, and Audiostatics. I find the Sound Labs have all the best qualities of the others and a lot of advantages. Sound Labs can play quite loudly, they are quite dynamic (macro and micro), the bass is prodigious and tuneful, there is no beaming of treble, and the sound of the panels driven full range is seamless. I find it easy to listen to music for many hours without fatigue. For me, there is no going back. They play every kind of music imaginable very, very well, from chamber music to big band to hard rock.
The backplates (interface electronics) contain two audio transformers, with a crossover at about 500 Hz, as the impedance variation with only one transformer would make the speakers virtually impossible to drive. The frequency ranges are combined on the panel, which is driven full range. Sound Lab can build or modify backplates for biamping if desired, which may result in greater clarity and dynamics.
As for power requirements in your room, I would have to say it depends upon your listening habits but anywhere from 100 to 400 watts are recommended. I think the 100 watts minimum should be considered as tube watts, although there may be exceptions. Higher powered amps have been used to good effect, and Sound Lab has used amps up to 800 watts on their speakers. There is no hard and fast rule as to which is better, tube or solid state. Rather, it may be a matter of preference. I've achieved excellent results with both, as have others.
Time for a disclaimer. I became a Sound Lab dealer a while ago, wanting to share my passion for the finest music reproduction and as a delighted owner. My enthusiasm as an audiophile spills over, which may sometimes get in the way of being an audio salesman, but life's too short for compromises. I had heard Sound Labs at some of the shows through the years and finally bit the bullet and have been happy ever since.
Larry, if you get to Chicago you're welcome to visit for a good long listen just to check them out, no obligation whatsoever. If you're in another dealer's territory I'll refer you to them, and you can still come and have a great time here. People who fly in know I offer complementary accommodations and offer full travel reimbursement upon purchase.
Brian Walsh