More updates (and questions) on the towers. I hooked up the HSU STF-2 sub to help them and it does make a huge difference. I don't like loud bass, but rather clean, tight bass and the sub delivers. It certainly sounds much better to me with the sub. I have them configured like this (no calibration, just by ear):
Speaker size: Small
Sub setting: LFE only (LFE+Main would probably not make a difference with Small speakers in this case -- correct?)
Sub gain knob: at about 10 o'clock (so under 50%)
I also tried Large speakers, sub set to LFE+Main, same 80Hz crossover and the setup sounded decent, but I figured why stress the speakers, free them up to do their job up in the highs and let the sub do the heavy lifting.
And my question ... the AVR is a Denon S900W and under Speakers/Bass there's an option "LPF for LFE" with a range 80-250Hz (default was 120Hz). This has nothing to do with the speaker crossover, right? It only applies to the true LFE channel on for example 5.1 material, not on stereo music. And I assume it doesn't have to match the speaker crossover. Is the default 120Hz a good default? I'm not sure what kind of frequency range is normal for the LFE channel.