Is this clipping?

My speakers are 16 ohm, 97db sensitive, in a small room. The amp is also set for 16 ohm. The volume control on my preamp seldom gets past 11:00, so I wonder if the amp is really clipping.

Unsound, I agree with your comment about sustained high volume on some rock recordings. Somehow this overloads either the amp or the speakers, or both.

Mapman, I agree that modern pop/rock recordings are some of the toughest to get right.

Getting back to my particular system (300B, SET, high efficiency full-range driver), I believe that all the components are well-matched, and there is no clipping. My suspicion is that this combination of components (as good as they are for traditional types of music) cannot faithfully reproduce the type of dynamics that are encoded in some modern digital recordings. I'm talking about the types of recordings that go from loud to louder to ear-splitting.
One interesting thing about these drivers is that there is never a hint of visible cone movement regardless of the volume. This in contrast to the clearly visible excursion of multidriver designs.

Dob,
I've read that paper and I agree. The 300B amp can reach the peaks, but can't sustain them.
Fortunately I have Spectron monoblocks in my other system!

Thinking more about recent digital rock recordings, seems to me that people make the mistake of associating compression and loudness with a poor recording. I disagree- they're supposed to sound that way. Unfortunately too much of the current audiophile equipment is unable to reproduce it well. This is one of the reasons we hear so much Norah Jones-type music at audiofests.
Last night I tried to listen to Katatonia-Night is The New Day on my 300b/single driver system, but simply unlistenable. Listening today through headphones- fantastic!

Unsound, Its probably a matter of your personal preference. Some of these recordings are supposed to sound loud and compressed. For better or worse, that's the artist's vision. The traditional criteria for a 'good' recording don't apply.