I've run an M900u on my TAD CR-1's and it gets them plenty loud (86 dB/2.83V/m). Prior to that I was using the BHK 300 Mono's, and I have not felt volume constraint. Now, they are not the best match for the TAD's, tonally (too light and zippy in combo), so I am back to using the BHK's (with the C900u preamp!).