I am wanting to improve the bass performance of my WiFi. I have Tannoy Venus mk2 speakers and separate pre and power Rotel 8708x amp. The speakers are rated at 100W each and the amp 400W total. The sound is really good except for the bass which is a bit lacking in depth and detail. I am looking at adding a subwoofer and have shortlisted the REL Tzero MKiii and the B&W ASW608. Looking for advice on whether these would really improve the system and which would be best. I like the small size of both particularly the REL, but am worried it would be a bit low on power (100W) and that the 6.5 inch driver might not be big enough.