Descent i sub -using both the LFE & Speaker Level Inputs simultaneously -is it safe?

MartinLogan Audio Owners Forum

Help Support MartinLogan Audio Owners Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Feb 4, 2014
Reaction score
Richland, WA United States
Descent i sub -using both the LFE & Speaker Level Inputs simultaneously -is it safe?

Hello gang,

Question for you concerning the operation of my Descent i subwoofer. I use it for both music (speaker level inputs) and movies (LFE input). My main 2-channel music amp is a Krell Vanguard which has no preout for a sub so I run speaker wire from its speaker level outs to the Descent i speaker level inputs. I also use the Krell for the Home Theater Bypass from my Pioneer SC-79 AVR. From the Pioneer SC-79 AVR I run a Sub Pre LFE cable to the LFE input on the Descent i. When I watch a blu ray I turn on the Pioneer SC-79 and the Krell Vanguard placing the Krell in Home Theater mode.

Since I first began doing this I have almost always unplugged the speaker wire from both the speaker outputs of the Krell amp AND the Speaker Level Inputs of the Descent i when I watch a blu ray because, I have the LFE running from the Pioneer SC-79 for the low end and I also have the Front Speaker L/R pres running into the Krell Home Theater Bypass mode so they are both powered up.

My question is, do I always have to unplug either the speaker level inputs or the LFE from the Descent i when going between 2-channel music listening and blu ray LFE listening? Every once in a while I forget to disconnect the speaker level outs of the Krell from the speaker level inputs of the Descent i when watching a blu ray using the Pioneer, thus I am sending 2 separate signals to the Descent i simultaneously - the LFE input AND the speaker level inputs. Does one of those two override the other when they are both receiving a signal? I don't want to fry anything internal on the Descent i. But, I am also tired of having to always unplug the speaker outs from the Krell to the speaker level inputs of the sub when switching from 2-channel music to a blu ray, and as I mentioned I forget to do it sometimes. Can I leave them both always plugged in without doing any harm to the sub? The owner's manual for the Descent i isn't quite clear about this.

Thanks so much - Dana
I assume not since I'm considering doing the same thing. Nothing is going to get damaged. The worst thing that could happen is the sub gets a sum of speaker level L+R, which it sends to its internal LPF, plus the LFE. If the bass management of your AVR is working properly (and set properly) there should be little if any bass content feeding your main speakers in home theater mode. No need to disconnect anything. Worst case, you'll have about 6dB too much bass. The speaker level inputs are high impedance. It's not like connecting two different amps to the same speaker (which someone actually asked Paul McGowan's "Ask Paul" recently).