2 subwoofer???

I've gotten great results with matched, dual subs. In addition to a fuller and more natural base, the addition of the second sub has resulted in a wider soundstage, added a bit more clarity to both instruments and voices and contributed to a smoother response in the low to mid-range. My listening room is over 3500 cu. ft. with many openings and a vaulted ceiling that climbs to 13 ft. The second sub has definitely made a difference in this large space. After experimenting with several locations, I concluded that placing both subs along the same wall, with each sub slightly outside of the LF and RF speakers respectively produced the smoothest and most natural sounding bass.

I’m using two identical 8” subwoofers with custom long-throw drivers and custom high-power class AB amps rated at 150 watts continuous and 400 watts + peak. I also own a 10” sub from a well known manufacturer that cannot compare with the 8” sub. The reason is that although the 8” sub is smaller, it uses a better amplifier and a higher quality driver which translates into more musical and a better performing subwoofer. Components used in this sub were selected for performance reasons without cutting costs to increase profit margins as manufacturers often do.

Recently, I auditioned a system that included four Peerless woofers (not active subwoofers) in a dipole setup with two per channel. The bass reproduction was awesome and the best I have ever heard. Using this a reference, the bass reproduction I’m getting from my two 8” subwoofers is remarkable by comparison considering their size vs the fact that there were four 12” woofers total in the dipole setup driven by amps with 250 watts per channel into 8 ohms. So in answer to the above…

Two smaller subwoofers can provide more stable/solid bass that would equal or surpass, etc. BUT, it depends on the quality of your subwoofers to begin with. In my case, two subwoofers have taken the sound to a higher level in every musically meaningful way: deeper, more robust bass that is more evenly distributed across the listening room; wider and deeper soundstage; improved clarity and definition of instruments and voices especially from the lower-mid through upper-mid ranges; overall the sound is more dynamic and alive.

Stereo or mono? Both of my subs are run in mono.

I agree with Bignerd, two smaller subs can do more work than one larger sub. Bass reproduction also seems to be more effortless with two. Two subs have no difficulty in
providing more than enough sound pressure to fill over 3500 cu. ft. of space in my listening room.

Connections, etc.:
With active subs, you can connect a Y cable to split the sub output at the pre/pro or receiver. Or you can connect one sub at the LFE output, and wire the 2nd sub w/ speaker wire as the left/right front speakers and connect those speakers to the sub.
Quality Subwoofers:
Hsu Research has earned good marks for its subwoofers. I have never auditioned one nor researched the amplifiers used by Hsu. Sunfire (Bob Carver) makes outstanding active subwoofers with powerful high quality amps. Some others in this group: Sonance, M & K, Velodyne, NHT, Martin Logan Descent, Vandersteen, Definitive Technology Supercube and Orb Audio’s Super Eight. All of these subs reach deep into the low range (to 14 Hz) and can move a lot of air. The specs don’t tell the whole story. A sub should be matched to the other speakers in the system to achieve the best performance. Ultimately, performance should be evaluated in your home not in a store or a lab. In some cases, I couldn’t tell the difference between subs rated lower (Hz) from ones whose bottom was a few Hz higher. Some 8” and 9” subs like the Sunfire SuperJunior and Orb Audio Super Eight outperform and sound much better than some 10” subwoofers. For music vs Home Theater use, I prefer a subwoofer capable of longer excursion for higher frequency reproduction especially in a sub/satellite system. For an in-depth discussion of subwoofer design check out Bob Carver’s “White Papers” at Sunfire.com under “technology” and “Sunfire True Subwoofer Whitepapers.”