[pjchappy]

What's the best (yet cheap) way of summing a stereo line-level signal, strictly for subwoofer use?  Want to bring my sub back to life.     Used to have an active x-over that did it for me.  Now, I have a passive x-over for it.

I haven't used it in a few years.  I may just go back to an active x-over, b/c of its flexibility. 

[MaxCast]

Does your sub's amp have l&r rca ins?

[Big Red Machine]

Why sum it?  If crossing over pretty low I would just use one or the other channel to get the bass output since it probably is in both channels anyway.