ssnkssnk, my vote is that the amp needs break in or that you are doing something wrong that once corrected you will be fine. I have not heard or used the amps, but most if not all of the articles and reviews I have read indicated that if you need more power, mono block them.
Benchmark AHB2 - To 'mono' or not to 'mono'
I own a single Benchmark AHB2 amp and have been considering another in order to run both in bridged mono mode, which will provide significantly more power to my speakers and presumably, greater dynamics. I've read in other threads where other owners (and perhaps others with opinions) had implied both positive and negative impressions concerning this approach. Assuming I'm not considering purchasing other amps at this time, does anyone have experience with both approaches and will you please share your impressions?