What to look for in a sub?

Hi,
Energy makes an awesome/tiny 8" sub for next to nothing. Paradigms are nice too. Any bigger and I'd consider Hsu. I hated my sunfire-buzz/humm and it danced around when worked hard. Pinnacle Baby Boomers are supposed to be really nice and tiny.
You will definitely benefit from a larger amp for the sub. 50 watts won't cut it. Janis Audio systems reccommends that by cutting all frequencies below 100hz you virtually quadruple the available power. Bass is power hungry. If your main speakers are getting 90 watts, your sub should get at least that but probably way more (depending on efficiency). Rule of thumb: you need to double your wattage to gain 3db, 10db increase will double the volume. Therefore, you need to approximately gain 9 x times the wattage to double the volume!

Thanks to all for all the information. Elevick, are all the subs you mentioned active or passive? I checked my little monoblock last night. It actually outputs 250 watts, not 50 watts. Thanks for the info on the Sunfire. It was actually on my list. Now I can take it off!

Check out the Mirage BPS-400 sub. (2) 12 inch active radiators with a 400 watt amp. It list for $1300, but Tweeter is selling them for $799. I only use mine for HT applications, but it does 'rock the house' very impressively.

I'd look at the REL Q150E. Small (12" cube), musical, good for HT and connectivity that no one else has. You can run hi and lo level inputs at the same time with cutoff set for hi level and full passthru for LFE (.1) info. Can be had new for under $800.

Another good one is the MJ Acoustics Pro 50. Another 12" cube, goes down to 15Hz, but you don't have the connection options of the REL.

Chris

I am really happy with the NHT Subone. $800 msrp, street price is less. It has line level and LFE connections that can be used simultaneously, and a controller box with the level, hipass and rolloff adjustments. This takes the electronics out of the vibration-filled speaker cabinet and puts them where you can reach them. Integration is seamless and the sub is great for music, too. It has a 250watt amp from Sunfire (no hum at all. BTW, if your amp hums, it's probably broken). I was reluctant to add a sub but I'm glad I did.