Good/best musical sub to match B&W 601's?

[kumimajava]

I've had a pair of B&W's 601 s3 for a few weeks now, and it feels like they would benefit from a sub. I only use this setup for music, so the sub needs to be "accurate" more than it is powerful.

Since where i'm at the audio shops don't have much to offer in way of subs, I have to primarily rely on opinions/reviews & recommendations... I know testing these things in person would be better - but it's not really an option.

My budget for the sub is around £300 - so i'm primarily looking at used subs.

I was considering one of the REL Q-series (Q150 or Q200), but i'm not sure that these are "musical" enough. On the other hand I though a (used) Storm or Strata (or mkII or mk III of either) would be better.

My main question is: do the strata/storm subs provide "enough" upper bass (the 601's are rated 70 hz at -3db) to match well with the B&W speakers - or do they perform well only at really low bass frequencies.

Also, any other recommendations would be welcome. For example, would the BK XLS200 be a good "musical" choice (i've heard a lot of good things about it in home-theatre setups)?

thanks in advance!

[Ian J]

I used to run a REL Storm with small Definitive Technology satellites and I would say that the sub's upper bass is excellent as the overall sound was seamless