Woofers getting workout, but no bass

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...

Do you know what is the port tuning? My guess it is between 25 and 35 Hz - otherwise you would not have such a problem even with vinyl, which I agree does tend to have some spurious LF due to the mechanical rotation of the disc once every two seconds...