73, you have it right in both of your last two posts.

The sub amp will power the sub no matter which input is used, and the main-speaker output terminals on the sub will have the lows stripped, and the receiver will only see the mains as a load, and only above the sub's X-over frequency, so all of this will decrease the load on the amp, not increase it.

The only thing to watch is that, usually, the sub will only have line-level outs when line-level ins are used, so to have the sub's X-over work for an external amp, you would need to use line-level from the receiver to the sub.

It's possible that, even with speaker-level ins, the sub could have signal on the line-level outs, but the opposite is certain to not work; the sub won't power main speakers with only line-level input.

------------------
Larry Fine
www.fineelectricco.com
My system