as I said in my Richard C. Heyser Memorial Lecture to the Audio Engineering Society in October 2011 (footnote 1), panel speakers behave in a mathematically chaotic manner, which leads to the production of subharmonics—this lies at –70dB (0.03%). The Quad ESL-2805 is considerably more linear than many tube amplifiers!
Cone drivers can have 3-10 % distortion.
As I reduce the distortion levels from my signal into my Quad 989's, they sound better and better.
SMSL M400 DAC - THD+N 0.00007 %
Bruno Putzeys designed preamp.
Neurochrome monoblock amplifiers - Total Harmonic Distortion + Noise 0.00043% 1 kHz, 55 W, 8 ", 20 kHz BW
All through balanced shielded signal cable and 20cm speaker cables.
The panels are raised to reduce floor reflection, with the 3degree tilt back removed.
Some argue that THD+N 0.00007 % is non sense as no one can hear that, though this is then added to the distortion of the preamp and then the power amp, cumulatively, plus any noise picked up through the cabling.
So what is the total level of distortion that you are listening to ?
The head in a vice sweet spot becomes a fallacy of poorly implemented systems. As does the lack of dynamics and bass.
Maybe I'm just more sensitive to listening to distortion than others, but listening to crossovers and loudspeaker boxes just irritates me these days.