Hsu Subs

Hi all. Which is the best Hsu sub for 2-channel music? The Hsu website claims the 1220HO is better than the STF or VTF series (I didn't see the site mention the difference between the STF and VTF series).

Also, is the 250-watt amp enough to drive any kind of music other than rap, or will I need the 500-watt amp? My monitors go down to 45hz -3dB.

I'd prefer to have a sub that has an internal amp (for space and cabling reasons) but if the 1220 is vastly superior to the internally-powered subs I'll go that route.

I've seen the recommendations on other used subs in the $500 range, but the Hsu seems to be well-regarded by a wide variety of speaker owners, whereas many of the other sub suggestions seem to be specific to speakers; that's why I've narrowed the selection to Hsu.

Thanks for your input.