The efficacy of using the AHB2 in mono mode driving a speaker with a 4ohm impedance was not clear to me from this review. The review briefly discussed this configuration and the low distortion associated with it, and continued to note that the speaker protection switched in and shut the output off. I am interested in using two AHB2's in bridged mode, driving a pair of 4ohm (minimum) speakers. I queried Benchmark about why they do not list specifications for bridged operation into a 4ohm load, and they replied to the effect that they do not list output specifications unless the output has been preconditioned, if memory serves me correctly, at 1/3 output for 1 hour. Under these conditions, the protection mode would be asserted, which seems to be supported by the review here. Benchmark further assured me that this pre-condition did not represent actual conditions when playing music, so I should be fine. In any case, my speakers will be protected. In fact, Benchmark said, the AHB2 can perform reliably at lower impedances than 4 ohms. So, my question is, can two of these in mono mode drive 4ohm speakers witih a sensitivity of 87 dB/1W/1m minimum?