There are so many ways to go on this. Budget-wise, the Adcom GFA555 (or later versions of the same 200 watt amp) work well. I am using one with my Kinergetics SW800 subs and it works fine. Also, the larger Parasound's are good sub amps for the money -- HCA2200 or the HCA3500 (350 watts). I used a McCormack DNA1 Deluxe with great results. I would think the 225 would kick ass. The key is to get an amp that doubles (or comes very close to it) into 4ohm loads. As I said, there are many good options. With my subs there is a definite difference in sound when using different quality amps (they are forward firing and a line source down to 200 cycles). I do not know if the Hsu's react the same way. Bryston 7B's are my planned upgrade when I get to that point. If you have the scratch, these would be a great way to go. I have heard that the Marchand x-over is very good but have no first hand experience with it.
sub power amp and crossover,which one?
i'am currently using a hsu tn1225 sub,would like to add another,hsu research does not have a large pwr amp at this time to run two sub,s.problems with their pwr amp manufacturer.anyway i'am looking for a pwr amp of at least 200watts per side and a high quality crossover.recommendations and model number's would be appreciated.thank you in advance.