I would ask how low do you want to go?
Unfortunately, no cable will assist in getting lower than 38Hz - you will need a subwoofer for that.
These speakers are approaching the limit of what a 6.5" woofer can deliver. Changing to a speaker with 8" woofer could get you down to around 28 Hz and a 10" woofer even lower.
I have Tannoy speakers with a 6.5" woofer (delivering low of 32Hz) on my A/V system and they lack the bass of the speakers in my Audio system which has an 8" woofer - with a low of 28Hz
Having said that, one speaker cable that does perform exceptionally well and will allow your speaker to perform at their optimal level is the gZero6 from KLE Innovations.
I highly recommend them and have reviewed them at length - see...
http://image99.net/blog/files/228f7609149d575dd8dd8d956511e7c2-57.html
There are other models of cable, but the gZero6 offers the best bang for the buck for your speakers.
If you would like a speaker cable more reasonably priced - try the gZero2. It outperformed my Van den Hul d352 10 gauge cable - providing a more detailed, faster and deeper bass.
See...
http://image99.net/blog/files/fac35e44c003d559714cdd73d86febf9-51.html
Also, If you do order either cable - ask for their Classic Bananas to be installed. It will probably be the last speaker cable you buy
Regards - Steve