It's best to use the same model sub in multi-sub systems. Why? Ease of integration, for one. Here's a snippet from the Subwoofer Connection Guide For A Multi Subwoofer System:...and in peoples opion what would be the very subs to use with this setup thanks i want to use 4 subs with 2 of them being the svs pc 2000 thanks
"When choosing the right subwoofers for your system, it’s a good idea to choose identical subs for optimal cancellation of room resonances, or ones of similar output level and design. Don’t for example mix and match a high quality 15” servo subwoofer with a cheap dual 6” bandpass sub that came with your “cubed” speaker system. Implementing an inferior subwoofer with a good one will limit your systems dynamic range and bandwidth to the weaker sub making your ears focus on the one that is breaking up and running out of steam. Mixing different subs will also reduce the success of canceling out room resonances since they will exhibit different amplitude and phase responses. Always select two well designed subwoofers (preferably the same) that are each in their own capable of filling your theater room with ample bass without bottoming out or running out of gas. If you can’t afford two subwoofers at the moment, buy one quality sub for now and add a similar capable one down the road when you’ve got the cash. IF you absolutely must use mismatched subs, it's important to try to chose models with a similar low frequency roll off slope."