Using multiple subs (two or more) is primarily about getting more uniform bass response throughout your room. Unless you are stacking your subs in the same location, you don't get a huge boost in loudness.
With a $550 budget, I would NOT recommend getting two $275 subs vs. one $550 sub. Two $500 subs vs. a lone $1000 sub? That might be a little different depending on the situation. But two $275 subs is not going to get you what you're looking for. I completely understand wanting to keep the price down and hoping that what you want will be possible at your budget. But it's important to manage expectations and understand that reproducing strong, low bass with high quality is NOT easy and it does legitimately cost some money to make it happen. Companies like HSU, Rythmik and SVSound are not gouging you on prices in the slightest. When one of their subs costs more, it's because the components used and the capabilities of the sub really do increase. There's a ton of over-priced, over-hyped junk in the world of home theater. You don't always get what you pay for. But with the good subwoofer companies, you DO get what you pay for and the higher price does reflect higher quality. $275 subs just can't make it happen. There's really no way around it. It just costs more to do what you're looking for
At over 3000 cubic feet, you have a "large" room. My favorite $500 sub is the Rythmik FV12. But it would struggle in terms of output in that room size. The HSU VTF-2 MK4 is a very close competitor to the FV12. But it too would struggle a bit with that room size. Even the SVSound PB or PC12-NSD won't be hitting reference volume in that room size.
But you also have to consider whether you getting anywhere close to reference volume (which most people don't, most people listen at an average 70-75dB, not the 85dB reference average, and most people keep the peak volume below 95dB, not the 105dB peaks of reference volume or the 115dB peaks in the LFE). If you tend to listen at lower volume levels, then the FV12 or VTF-2 MK4 might do ok. The SVSound PB/PC12-NSD almost certainly would do ok so long as you're not trying to hit reference levels.
One really nice thing about the Rythmik FV12 is that you can literally crank the volume as high as you like. Thanks to the excellent engineering over at Rythmik, the FV12 will simply play as loud as it can, but will then limit itself and not try to play any louder. That's a great "safety" feature in a situation like yours where it's entirely possible to set the volume higher than what the FV12 can actually play.
It's tough. For a room that size, I'd be pointing you towards an SVSound PB/PC12-Plus or a Rythmik FV15HP, or at the least, an HSU VTF-3 MK4 or Outlaw LFM-1 EX.
Ooh, that reminds me though, the Outlaw LFM-1 Plus would be a really, really good choice for you! It's at $549 + shipping right now. Sadly, the B-Stock sale is sold out. But for your $550 budget and your larger room size, I don't anything will top the LFM-1 Plus. It's virtually identical to the old HSU VTF-3 MK2 - it's got a little more amp power than the current VTF-2 MK4, which helps in a situation like yours
Yeah, the
Outlaw LFM-1 Plus is a winner if you're sticking within your budget (going a bit over when you factor in shipping, actually). Again, you won't be hitting reference volume, but you won't be starving for output either.
And two $275 subs won't hold a candle to the LFM-1 Plus, I can promise you that!
