I use Crown XLS series amps for my diy subs. They don't have helpful dsp, though, particularly if you need to set a protective high pass filter (as is fairly common with ported subs to prevent over excursion below tuning). You can add a miniDSP unit to the Crown, tho that adds expense and I'd minimize it to get Polk subs running. A used Behringer dsp-enabled amp (they used to be called the iNuke DSP series, think they're NX with a "D" designation now) may be more useful and cost effective but may come with a bit of fan noise. I am not a fan of plate amps, unless they're top quality like SpeakerPower maybe. Overall I think it's time to think about new subs, tho.
