Hi my name is ***** ***** I will be the expert working with you today to help you understand and get the correct subwoofer for your sound bar.
You can prefer any of the brands they depend on what company you prefer
we have yamaha, JBL, Pioneer they are all compatible with your sound bar all you have to make sure the cable is supplied for the audio subwoofer to connct to the subwoofer port at the back of the soundbar.
check these links
let me know if you have any more question.
http://www.ebay.co.uk/bhp/active-subwoofer best options on ebay UK
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