What you experienced is typical for those coming to realize there is "high current" amps. 86dB is definitely on the inefficient side. 3dB is exactly double the sound output at the same volume level. Even without a stable impedance the pioner 50 would have some problems.

Some of these guys wouldn't admit there is high current design if there life depended on it. It don't take being biased to know if your amp is clipping or not anymore due to the speaker load. I wonder if mrycraft has ever owned any stereo gear. What Hertz stated was pure fact, he didn't say any of the things I did about better bass and control, though I suspect that was also a result, these things maybe you could shout "biased" because they are more subjective. But one would certainly know if there amp isn't clipping anymore when all other factors remained the same.