I have owned both the ATC1, ATC 5, ATE 2001 pre amps. As well as the ATM 2 (Kt 88), ATM 211 mono blocks, and ATM 300b anniversary amps. I love their stuff. The ATM 2 is a brute of a tube amp, I recently sold it, and the ATC 1 pre amp, just because I had too much gear and went full in on SET amps.
I'm keeping the rest of the gear. Competes with Shindo and the other Japanese high end gear.