Hello I use a m33 and m23 drive kef reference 5 meta , and never have been so happy and thought i would buy amps in the 20-25k range to use with speaker but the sound imaging and dead quit background is beyond any amplifier i have owned ..now the reviews have some weight about not as engaging as others, but I found its so clean and precise the cd quality is not hidden the best discs will shine with imaging and clarity not approachable you will be very pleased with the 33 ..class D ... no class A performance Gone is the 200 lbs 1500w amplifiers ..Mabe