Using Two Subwoofers with Two 2-Channel Amplifiers.

My vote would be "yes" to using two sub woofers.

In my previous setup I had a "Y" cable to combine the left and right preamp outputs into a single feed to the sub.  That worked well.

But with my latest setup, which is much higher end, my dealer and a number of my audio buddies argued for me to deploy a pair of subs, one for each channel, and I must say, the "visceral" experience is better, especially when listening to classical music, where the double bass sounds might be coming from one channel.

When I was struggling to integrate this pair of subs, at one point I moved them to behind the listening position, and the result was not good.  Most of the music coming from the main speakers was well positioned, but the sound stage for the low frequencies was "all over the place", the "sound" coming from the front, but the "feel" coming from behind.

I use 2 REL subs but they're both mono as the aural "ques" for bass position in the soundstage, in either classical or jazz or anything else, is unaffected in my system...the plus is since the subs are doing the same thing they act as moderators for each other by canceling standing waves, which would not happen if only one sub was producing it's stereo signal without the other sub...the subs are set at a low enough frequency (matching where the mains roll off) that stereo imaging is still spot on.

Two channel with subs hard to integrate them together.  But if done correctly can be really amazing.  I strongly recommend:

1) using same amp driving all channels.  The highs, mids and bass.  

2) same interconnects and speaker cables for all unit. 

3) no electronics crossovers Only passive crossovers.

Alot of people think that 60hz and below the bass doesn’t matter when it comes to coherent, huge mistake.  It makes a biggest differences when it comes to two channels critical listening.   

+1 wolf_garcia regarding a monaural or summed below an approximate crossover point depending on the speakers and the room.

With the exception of subwoofers by REL manufactures include the convenience high level connectivity for those who lack source RCA outputs, experimentation should be seriously considered.

Review the subwoofers manufacture instructions when using high/amplifier level connections. Connecting both amplifiers Left channel outputs to one subwoofer seems unusually redundant.

With an honest respect to zipost's experiences. My only sub installation with very small mains that began their in room measured falling off at 97Hz stereo high level connectivity did sound subjectively better to the owner.

With main speakers falling off below 50Hz monaural has always produced a more desirable effect in my experience. It also liberates subwoofers for the always unique crawl test sub locating and an overall improved performance in speed and room node control.   

I am using two stereo JL Audio F-113 subs and I feel that 2 subs fill the room much more than one does. I have mine located close to the mains.

ozzy