I must have missed this thread completely. But regarding the bass, I recall someone (Home Theater Magazine or SV) setting the Classic Four as "active" or at least "partial active" bass by using a separate external amp and crossover and removing the metal jumpers from binding posts. This does not remove the internal XO, thus I mentioned "partial" active. But the external amp and XO powered the woofers. And this would produce lower bass Frequency. So the 27Hz is probably with the ext amp and XO powering the woofers.