Hi Gents,
Just when I thought I'd put this thread to bed, I've been bugged for a while that there is not much low bass with the Zone 2 "PC" speakers. The inexpensive JBL Loft50s just don't get down (37 Hz is spec'd but I don't believe there's much output down there).
Eventually I tried feeding a surplus Klipsch Sub SW-112 I have kicking around via the second RCA Sub Out on the Denon S900W. Unfortunately, even though the manual suggest using this output for a Zone 2 Sub, it's really tied to the Mains. So if you turn down the Mains, both Subs get pulled down as well. So that was a fail.
When I was taking the RCA Sub feed out of the SW-112, I noticed High Level Inputs which I had dismissed using some time ago. I decided to look into trying this method as I've never used it before on any of the systems I've owned, or put together for others. There seems to be a couple of trains of thought on the Web. Some folks say this is the only way to set up your Subs (like REL); some think you should use this method for Music while using RCA for Home Theater; while even others think this is an antiquated technique that's substandard. I looked on YouTube and many forums for something definitive, but of course it's a mixed bag.
Even amongst those who believe in this connection method, there are two wiring schemes if the Sub only has High Level inputs and no outputs. One has the speaker cabling go from the receiver speaker out terminals to the corresponding High Level Sub inputs, and then from there onto the Speakers. The other has you run the speaker cabling go from the receiver speaker out terminals to the corresponding High Level Sub inputs, in addition to the original cables from the receiver speaker out terminals to the Speakers. (Both feeds are from the same speaker terminals.) I decided to try the latter as the Klipsch SW-112 Manual says:
“HIGH LEVEL” Connection - If your receiver (or pre-amplifier) does not have a Subwoofer Pre Out, Sub Out, SW Out, etc. connection, you can connect the SW subwoofer via the High Level Connection. Using 16 gauge or larger speaker wire, connect the RED “positive” (+) terminal of your amplifier’s LEFT channel to the RED (+) terminal of your subwoofer’s LEFT channel (High Level In). Connect the BLACK “negative” (-) terminal of your amplifier’s LEFT channel to the BLACK “negative” (-) terminal of your subwoofer’s LEFT channel input (High Level In). Repeat this procedure for connecting your amplifier’s RIGHT channel input. Take care that no bare wires from any of the connections touch any other terminals, or each other, as this could damage your equipment. This connection to your receiver will be to the same terminals as your main speakers are connected to.
I connected it this morning and to my amazement it works great. I've set the crossover at 80 Hz. and the Gain at 50%. (I may tweak it further as time goes by and I listen to it with the Sub more.) It just adds the missing bottom to the tunes I listen to while on my main PC in the Man Cave /Junk Room. Strangely, I listen to this (now) 2.1 system more than any of my others (although the 7.2.4 Atmos System in the Games Room is close), and it's just cobbled together.
I hope this post helps others who were nervous about trying High Level Sub inputs for the first time. I'm very happy with it.