You might try going clampless. I just demonstrated the merits of this to a HW-19 Mk 14 user yesterday, first with a DIY spotmat and then with my Boston Audio Mat 1. In both cases the sound opened up a lot without the clamp and there were no detectable downsides. YMMV and all that, but I gave up on clamps on my TNT Mk 2 quite a few years ago. Good luck, Dave