@pinwa I was at an audiophile society gathering a few months ago and we were listening to different genre of music favorites through a great system consisting of Luxman monobloc’s and Quad I believe 2729 speakers. The music presented was some of the best I had heard it. One member suggested a specific bass track be played and when the host played it at a moderately loud volume, there was a loud, scary "flapping" kind of resonance coming from the speakers ! We were all surprised and it was fortunate that the host muted it immediately. Luckily, there appeared to be no damage to the speakers, but the host was particularly unnerved about it. Apparently, there is a low frequency resonant point on those speakers that the specific cut of music hit. The host said he had never heard that on anything he’s played, and he’s had these speakers for a few years. I have the Final Model 12+’s and am still in the 350 hour break in process, but I haven’t experienced that with my M12+’s even playing Bela Fleck’s "Flight of the Cosmic Hippo" fairly loudly. I’m surprised at the bass output of these M12+’s and so far, am very pleased with the sound. I hope I don’t run into any arcing when playing loudly !