Subwoover and Quad L-Series Speaker comb. help


I hope someone can help me on this.
here is a short description of my system.

Meridian 586 CD Player
Meridian 565 7.1 Z3 Processor
Meridian 565v Video Switcher
Monster HTS 5100
Sunfire Cinema Grand 5 Channel Amplifier. (200 X 5)
Quad 22L Front Speakers ( 300w | 30Hz-24kHz )
Quad 12L Rear Speakers ( 200w | 45Hz-24kHz )
Quad L-Center Center Speaker ( 120w | 70Hz-24kHz )

I am very please with my system. It took a great amount of time to setup ;) but it was well worth it. but I am missing the lower range. you know the "down below". I do not want to crack my windows with too much base. I just want to fill the void. I heard people mention that the sunfire supper junior would be a great fit for me. some say it would not be strong enough. but I really do not want to much bass. my quads are really well balanced and i would love to keep the harmony it has at the moment, all advice on this would really be appreciated.
Ps. I know Quad is making a L-Series Subwoofer but it is not available yet.
snappy
I would use REL , which will reinforce the low end without affecting the rest of the range. Which model will depend on your budget and how much bass you want.
Just an update I demoed the REL and the new Sunfire Ture Subwoofer EQ this afternoon and decided to get the new EQ series I also listerned to the EQ signature and a meridian 1500. I wish I had acces to the meridian 2500 sub but nobody arround had one I knew. I will keep you all up to date on recieveing and finishing setup on the new sunfire EQ with the Quad L-Series
Snappy, I'm interested in how the 12Ls are working for you as surrounds. I have the 21Ls and Quad L center, but thought the 12s wouldn't be suited as surrounds because they are rear ported. Do you have them attached to the walls or on separate stands? Also, which REL did you demo and what did you prefer about the sunfire? Thanks.