JMS,

It would not really surprise me - one way or the other.

With capable full-range speakers running in plain old stereo mode, you may or may not notice the presence, or absence, of a sub (or subs) depending on source material and other factors like room acoustics etc.

In my main system I'm hard-pressed to notice a difference between subs out and subs in, in stereo (with front mains set to large / small 40Hz respectively.) About the only way that I can tell the difference if I were to walk into the room not knowing the current settings, is to lay a hand on the subs to "feel" if they active.

Now 5.1 movies are a whole different ballgame - because of the LFE signal. (Not the redirected bass since I run everything large across the front - except for the opening credits in the Hulk, which is the only soundtrack that I've ever played at my "normal" levels that caused my centre array audible distress. Running them small 40 Hz for that movie cured the problem.) Removing the LFE signal is more than noticeable - it's lunch bag letdown in the worst way.

So to return to your post, it seems that your sub is making a true contribution in stereo mode - either because your mains are either not capable of, or are not set up to, reproduce the usual low bass in stereo recordings. No surprise that you'd notice its absence.

(ps. So why not add another LFM-1 to the living room stereo system? Move your existing one to see how it sounds. Might be a worthwhile upgrade!)

Regards.

Jeff Mackwood