hybrid solid state amps

ButlerAudio.com - outstanding Tube/MOSFET amps. I have their TDB-5150 and it is real peach of an amp. Cruise over to their website and read about them and their revolutionary circuitry...

6 Moons did a very favorable review.

-RW-

Pathos amps use a tube front end and ss output stage. Don't know about their size and cost, though.

I assume you mean power amps, but the Pathos Classic One integrated fits your bill, too.

Marty

Musical Design

http://www.musicaldesign.com/MD_T100.html

LSA designs is another. I have heard a few and the Moscode is a lovely amp, but not that cheap. Pathos make few, from the Classic to the TT, which was known as the Twin Towers, the Logos, Inpol, all integrated, right up to the Incontrol monoblocks.
I have the Inpol and it truly is a wonderful amp, 50 watts of Class A power, refined detailed, tonally rich. I can't really make any complaints at all. It is more than your price limit, but within it, second hand. If you can manage with 35watts, the TT is great too. The logos is Class A/B and to my ears, markedly inferior to the Class A amps.

There is also the Aesthetix Atlas. All of the reviews have been favorable and it's a great sounding amp.

Good Luck!