I find my Triangles mate best with gear that is a touch towards the warm side of things.
I get it currently off my main system via the ARC sp16 pre-amp, the only tube piece in my main setup. Just a touch of warmth but nothing overt. A nice combo with the Class D amp.
They do very well also of the TAD Hibachis which add a fair amount of tube like warmth to the sound.
I really liked them off my old Tandberg TR2080 receiver which had a lovely warmth to its sound when I had that.
I will run these off a tube amp someday just for something completely different and fun, maybe a flea powered SET, whenever I finally get around to it.
I find the flaws with teh little Triangles to be mostly of ommision with the lowest octave but the setup and placement can effectively alleviate that, at least in a smaller room. I've used them in my larger room where the OHM 100s are currently along with a sub and that was a formidable pairing.