Woofers getting workout, but no bass

Could be feedback. If you put the needle down on a record that is not turning do you still get woofer movement? May have to move your turntable. I had the same problem and that fixed it.

Very likely it is simply a matter of ported speakers and the sound is lower frequency than the port tuning frequency on the speakers.

When you have sounds below the tuned port frequecny of your speakers then the woofers flap around uncontrollably and make almost no sound, which is exactly what you have. Sadly, this flapping around will add plenty of IMD distortion to any music you play becuase the speaker drivers are operating way way outside their linear range when they pop out of the speaker in the way you have observed - look for a big port on your speaker probably tuned around 30 Hz to maximize bass extension...

Either you can filter out all the LF electronically or select a different design of speaker...

Yes, ported speakers are more commonly susceptible to this kind of thing from what I have observed over the years, but I think the problem can affect other designs using dynamic drivers as well.

I think since porting is a very common approach to extend low end response on speakers that the problem is more common there, but not a result of the porting itself.

Not sure about IMD distortion, but it still might result in faster amp clipping even with a planar or electrostatic speaker with similar frequency response I would think.

Are you saying a ceedee playing down to,say, 25Hz will also cause excessive excursion? I think that ported speakers may be more susceptible, but that doesn't tell the hole story, IMO.

"Are you saying a ceedee playing down to,say, 25Hz will also cause excessive excursion?"

No, its a vinyl playback artifact not present in CDs.

"I think that ported speakers may be more susceptible, but that doesn't tell the hole story, IMO."

I would agree.