Need more bass response

If jazz sounds great but not rock, it's probably not the system but the recordings that are causing your consternation. "From the Cradle" is hardly a mastering wonder. (Not to brag, but I've heard EC do most of that material in a club, so I have some basis for comparison.)

I certainly wouldn't do anything that would mess up your jazz reproduction. Adding a sub might be the ticket, though your Silvers are no slouch. Rearranging the room could help, but if it's your living room that's probably a no-go.

Here's a radical suggestion: Get an equalizer. Bypass it for good jazz recordings, but tweak it a bit on other stuff to see if it improves things. (Purists will howl, but it's not their ears, now, is it?)

Power conditioner? From a guy who has his doubts about cables? C'mon, you know better than that!

One thing you're absolutely right about, Ax: None of us is the Oracle (who, it turns out, was constantly high, so maybe some Agoners may have more in common with her than they think!). You gotta make your own way. Others will tell you to be openminded, but I'll put in a good word for your healthy sense of skepticism. Best of luck.