Actually, after spending a whole day on this, I think I have isolated the problem. There is something wrong with the LFE connection on the back. When the cables are plugged all the way in, the bass is almost nonexistent or “anemic”. However, if I pull the cables out just slightly, the bass kicks to life and the speakers sound as they should, with plenty of bass and low extension. However, leaving the cables in this position, the speakers no longer turn themselves off after a period of inactivity (i.e. the blue light stays on). I’m going to have my home theater guy who hooked these up check the LFE cables but is there.a way to tell if this is the fault of the speaker vs. the cable?

Sorry, never heard of anything like that. Are the cables non-standard with a long pin maybe?

Hi, I think the pins are pretty standard...my HT guy ran cable through the wall and fitted the end with the connectors shown. The fact that I have to pull them out slightly from BOTH speakers for the subs/bass to kick in at all makes me think it's a cable issue rather than a speaker issue so I have him coming out at some point to look at this. Thinking back, I wonder if a poor connection to the LFE jack caused the LOUD rumbling sound I initially heard when I first got the speakers after powering down the system on a couple of separate occasions...