Thank you all for your responses.
I played the test frequencies on the Stereophile test CD and with the Pioneer, 40 hz is somewhat audible but actually more "felt" than heard. The Sonus Faber Liutos are producing the 50 hz tone on that CD but at greatly reduced volume compared to the higher frequencies. I've got an SPL meter which I'll be using as I proceed.
One thing I'm pretty certain of, is that the frequency adjustment knob on the back of the subwoofer is not accurate. With the dial set to 40hz, if I put my ear to the port I can hear higher frequencies. I hardly expect REL quality, but I do think the Pioneer has potential given enough experimentation. I've got lots of feet and spikes to play with, too.
While I try to get off the merry go round, and I always place primary emphasis on the music, rather than the gear, I'm beginning to think I could use a 12-step program tailored to audiophiles. :)
At least for the past few years, my audio obsessiveness is inexpensive or free tweaking.