Hi..angynagpal,
Don't worry about the quality of sub woofer, coz its par excellence.I have tested it with so many DTS demo DVDs and other music CDs containing deep bass, even with the CD received from our FM Amp_Nut - MR.Dinyaar(Hats off to him for providing me such a nice CD-its a testing engine..
..).Its awesome..I am sure you will never get disappointed.Even after purchasing this system, last week I got a chance to audition Denon 1713 with Polk audio TLI 2600 and other KEF speakers also , at Profx showroom and I was very much satisfied with my decision.One thing I have noticed with Wharfdale is that they are very melodious and each & every freq sound is delivered perfectly.