100W+ solid-state amps known for beautiful mids

If you can get a 200W+ amp, get it.
the headroom you will need.

Buying based on watts is not a good formula. 

Like someone else mentioned, I have Keith Herron's M1 monoblocks.  They are "only" 150 watts each, but they have a very large toroidal transformer that provides all the headroom I need.  Previously I had Rogue Audio M180 tubed monoblocks (which I loved), but the M1's provide all the power I need and are cleaner and more detailed than the M180s.

If my budget allowed, I'd be more than happy with a 100 WPC darTZeel amp.  Some of the best midrange I've heard came from a 48 WPC Line Magnetic 805iA integrated powering Harbeth 40.1 speakers.  Having plenty of power certainly can help in the right design, but there's so much more to an amp than how many watts it puts out.

I searched long and hard to find an amplifier that sounded good with my Martin Logan CLS IIz. After trying numerous high-end tube and solid-state amplifiers I settled on the Classe CA-200.

@peguinpower. I had the exact opposite experience with the Pass X150.8 and Audio Research.  I found the ARC to have wonderful mids and the Pass very sterile lacking any midrange magic.  Could be system dependent but it's crazy how we have totally different experiences.  

Having owned and auditioned lots of amazing SS amps over the last 50 years, while some are very good. If you want great midrange just get a tube amp. I stayed away for decades until finally Audio Researched produced the auto biasing and microprocessor controlled tube amp that had good tube life… Reference 160S. My question to myself has been, why didn’t I do this decades ago! My system is now all tubes, and it is more involving and satisfying than I ever imagined possible.

@gryphongryph I am using VTA SP14 which is the predecessor that Don Sach's is based on. My speakers are ATC SCM19. The founder of ATC, Billy Woodman recommends 100W+ with high damping factor on his speakers, so I'd like to adhere to his recommendations. For the reason, I think it's headroom, since transients require a lot of current.

@ghdprentice I believe that my speakers are incompatible with the vast majority of tube amps. I'm taking advice on amplifiers based on the ATC founder Billy Woodman, in that ATC speakers are best with 100w+ class a or ab solid state amplifiers with high damping factor. I think the problem is that most tube amps have extremely low damping factor, which apparently doesn't mate well with ATC speakers, though I have yet to try myself. So for now, I'd like to stick with a solid state power amp with a tube pre-amplifier to get at least some of the tube magic in! If that doesn't pan out, maybe I'll try one of those monster 100W+ tube amplifiers like the Rogue 100, and if that doesn't work, then I might move on from ATC and try something more tube friendly like ProAc bookshelves.