Anything which prevents clipping must by definition start limiting the signal before it reaches the point of clipping.
Agreed. But it doesn't have to start acting way before the onset of clipping. The threshold can be set so it is right below where the actual clipping would occur.
Since clipping does cause distortion, the clipping prevention causing some doesn't make much of a difference, it only happens at a slightly lower level.
And more importantly, we want to prevent clipping at all costs, at least to protect tweeters, if not other things, including the ears.
A good clipping prevention that acts by limiting the gain at the input, would not cause so much distortion anyway, and that is preferable to what's caused by clipping.
This means distortion sets in at a lower output level, even if it is 'smoother' than clipping.
Just a slighty lower output level. It needs to be properly calibrated to act right before the real clipping occurs. And if the action is to limit drive level, then the extra distortion can't be that much.
Clipping itself is not especially noticeable,
I would think it is. When doing PA, sometimes the drive level can be pushed too far and noone really notices, when so many amps and speakers are used. And then tweeters can be harmed, or worse...
temporary blocking. This suggests two solutions:
1. if you have severe clipping than you need a bigger amp or more efficient speakers or a smaller room or a hearing aid.
2. if you have mild, occasional, clipping then you just need to ensure that the amp recovers quickly after each clip event.
If an amp is used for PA sometimes, and not only for private listening, clipping is likely to occur.
I will look into limiting the input drive level. This is the best way to go I think.