I have a Marantz SR4200 receiver and Wharfedale Diamond 8 speaker package. I am now looking to add a sub but am not sure which model to go for. The options that I am considering are: Wharfedale Powercube 12a - seems like an obvious match for the rest of my speakers, and I can knock a decent chunk of money off the RRP by buying online. MJ Acoustics pro 50 or REL Quake,- I know that these are generally more highly rated, but I have some reservations about paying as much for the sub as I did for the whole package! Would it really be worth paying so much extra for either of these models? One important factor is that I am primarily concerned with movies rather than music - the 8.3 floorstanders give an impressive amount of bass so I don't think that a sub would make that big a difference with music (or have I got this wrong?). At the moment I am leaning towards the Powercube, but I am still not completely sure, so I would be grateful for any advice. Cheers!