Yesterday I was listening to some Ricky Lee Jones (Danny's all star joint) at a volume level of around 75 & was getting a large amount of distortion from the front right DSP33. It sounded initially like a mid/bass driver had gone as it was worst on the bass transients, but closer listening revealed that the high frequencies were reduced in volume as well. More out of hope than expectation I swapped the R & L leads.......& hey presto it sounded fine, & continued to do so when the leads were swapped back!
Does anyone have any idea what may have been happening?

568.2mm, DSP6000, DSP5200HC, DSP33 rears, HD621, LG G3, Sony UBPX800-M2, F80.