Is that a generic comment (ie: like amps usually do x) or one specific to this one?Usually it goes into protection, I.e. it turns off.
I have heard amps that are current constrained simply start to sound "confused" - midrange loses focus, imaging and staging collapses, and yet it seems to be working fine - at standard listening levels ie: around 72db SPL at MLP or circa 4W average to the speakers...
The same amp is known for shutting itself down when running bench tests for more than 30 seconds at 5W into a 4 ohm load.... yet into my 4 ohm nominal speakers, with minimum impedance at 1.6ohm, and crossover to the woofer dropping to 3ohm - they ran just fine at around the 4W mark (estimated - based on volume level and speaker specs) - well sort of just fine - with the confusion of the sound / reduction in sound quality.
So it wasn't enough to trigger protection circuits, but it was enough to impact sound quality - if it was on a system I was not intimately familiar with, I would have had difficulty telling that there was a problem... there are plenty of systems that under normal circumstances sound the way my own did with this amp feeding it - but on my own system I know what it should sound like, and I know that it can do better.... and swapping in one of my more capable power amps instantly resolved the problem!!
Hence I ask more questions about difficult load capabilities, and the impact of difficult loads on amp performance. (in my case I presume there was a substantial rise in some form of distortion that was messing things up, but not to the point of clipping, where distortions are shockingly audible)