You're dealing there with a matter of likely increased efficiency, with more drivers or volume, power, etc. And, since the woofers are in pretty much the same acoustic location, it acts acoustically like a normal large subwoofer, in space. So, whether the output, freq depth, and ability to fill volume in a space is right with any given sub, in any given space, is a key there. OTher than that, how quality is the actual product and sub performance on it's own...is it accurate and fast enough as a music sub to integrate with the system...does it hold together and make an effective home theater dynamic subwoofer, capable of reproducing explosions and heavy dynamic loads, etc?? These things are obvious considerations.
If all of the above are covered well with single subs in a system/room, then the question of multiple individual subwofers is more relevant for addressing issues like more needed bass volume/energy/output in a given space, getting more efficiency from the system (more muscle from the bass), and helping the systems bass acoustics, by trying to more evenly smooth out he bass modes, which are inevitable in most any practical size home theater environment. In case of the last issue, I think it's been proven that carefully place multiple subwoofers in a room, has some key acoustical benefits/advantages, that are worth noting.
My problem with multiple subs placed anywhere other than in either one location up near the front of the system, or flanking as stereo subs near main speakers, is that of PHASE ISSUES, from multiple seating locations, in relation to mono subwoofers at different distances from the listeners ears!!! And I've proven that this can be a BIG challenge to set up right, particularly in multiple seating arrangement setups! (once had a client who had two mega buck subs setup in different locations in a room, and the subs weren't making any noticible bass impact across the spectrum! The problem?..they were out of phase with each other, and at varying seating location distances, in relation to the speakers and the subs themselves! -an EASY problem to run into, I assure you - relocated the subs up front, fixed the problems, and super depth, impact, coherence, speed and effectiveness! problem solved, thx)
I MUCH favor keeping the subs in an inherent good singular location in the room, preferably up front (where crossover blends are MUCH MUCH easier), and where I can EQ the subs issues out then, and keep the phase and coherence of the system intact, regardless of the planned seating locations chosen. I think the vast majority of audio enthusiests would find this approach a much easier setup approach, with more foolproof results, and less chance for problem - better matching and blending, and so on.
Then again, if anyone wants to tell me how they can avoid having phase cancelation issues between two(or more) mono subwoofers, placed in half spaces of the room boundaries (sides, front, back, etc), with several rows of seating locations (or even sitting right next to one side sub, vs the one in the center front), in relation to other seats, and still not have phase cancelation issues, and lack of coherence between bass crossover and main speakers crossover frequencies, etc, then I'd sure like to know about! Cause I find nothing but problems with the multiple mono subs placed midwalls, all around the room, unless dealing with 1 or two seating locations only. And even then, nothing a good DSP EQ can fix on it's own, anyway...so what's the point, I've always asked?
Much rather do multiple subs around the room, near each monitor, run in stereo individual channel configuration for each speaker in stead, in that case.
If all of the above are covered well with single subs in a system/room, then the question of multiple individual subwofers is more relevant for addressing issues like more needed bass volume/energy/output in a given space, getting more efficiency from the system (more muscle from the bass), and helping the systems bass acoustics, by trying to more evenly smooth out he bass modes, which are inevitable in most any practical size home theater environment. In case of the last issue, I think it's been proven that carefully place multiple subwoofers in a room, has some key acoustical benefits/advantages, that are worth noting.
My problem with multiple subs placed anywhere other than in either one location up near the front of the system, or flanking as stereo subs near main speakers, is that of PHASE ISSUES, from multiple seating locations, in relation to mono subwoofers at different distances from the listeners ears!!! And I've proven that this can be a BIG challenge to set up right, particularly in multiple seating arrangement setups! (once had a client who had two mega buck subs setup in different locations in a room, and the subs weren't making any noticible bass impact across the spectrum! The problem?..they were out of phase with each other, and at varying seating location distances, in relation to the speakers and the subs themselves! -an EASY problem to run into, I assure you - relocated the subs up front, fixed the problems, and super depth, impact, coherence, speed and effectiveness! problem solved, thx)
I MUCH favor keeping the subs in an inherent good singular location in the room, preferably up front (where crossover blends are MUCH MUCH easier), and where I can EQ the subs issues out then, and keep the phase and coherence of the system intact, regardless of the planned seating locations chosen. I think the vast majority of audio enthusiests would find this approach a much easier setup approach, with more foolproof results, and less chance for problem - better matching and blending, and so on.
Then again, if anyone wants to tell me how they can avoid having phase cancelation issues between two(or more) mono subwoofers, placed in half spaces of the room boundaries (sides, front, back, etc), with several rows of seating locations (or even sitting right next to one side sub, vs the one in the center front), in relation to other seats, and still not have phase cancelation issues, and lack of coherence between bass crossover and main speakers crossover frequencies, etc, then I'd sure like to know about! Cause I find nothing but problems with the multiple mono subs placed midwalls, all around the room, unless dealing with 1 or two seating locations only. And even then, nothing a good DSP EQ can fix on it's own, anyway...so what's the point, I've always asked?
Much rather do multiple subs around the room, near each monitor, run in stereo individual channel configuration for each speaker in stead, in that case.