Absolutely agree with Millercarbon, except I prefer sealed to ported subs (not sure that it matters particularly in a multiple sub array, it's just my preference). I have two Rythmik 12SE subs and one dual 10" sealed DIY sub in addition to the 10" woofers in my full-range Kef Reference 207/2 speakers. Using the subwoofer crawl I was able to dial in bass response below 200 Hz to ~+/- 2dB at the primary listening position. Multiple subs is not a cure all, but it is effective in managing room modes at a single location.
Mismatched Dual Subwoofers
Has anyone ever tried integrating dual subs with two different subs that are different sizes? My anthem STR only has Left and Right sub outs so I assume using that will be problematic. Would love to hear other’s experiences with dual subs!