Hi Fred,

If you graphed the frequency response, the non-linearity should show up as a gently rounded hump in the frequency response, likely starting around 100 Hz and reaching a peak that's perhaps 6 dB to 10 dB higher at 60 Hz, then gradually rolling off as you get to lower frequencies.

There might be increased harmonic distortion, but the reality is low-bass distortion is really hard to detect with music or effects until it rises to huge levels.

Regards,

Alan Lofft,
Axiom Resident Expert (Retired)