I have 2 Wharfedale D330 tower speakers and I need a subwoofer with deep bass...i have an eye Polk audio HTS 10 or Wharfedale SW-12 ..any experience with this subs or something else?
I’d go with a company that’s more dedicated to making subwoofers.  The SVS SB1000 Pro is $500 and will get you down to 20Hz (-3dB), and they offer a generous and truly risk-free trial so you can see if they give you everything you’re looking for.  Best of luck. 
Thank SB1000 Pro would be good for low levels?
There are a number of challenges in getting satisfactory bass response beyond the brand of subwoofer.  I wrote about them here: