Reddit mentions of URBEST 15Pcs Right Angel Speaker Terminal Clip Connector 2 Positions Audio Cable Push Button Type

I had the same issue with our 5.1 soundbar and the wireless 8" sub. It isn't bad at all, but I have several subs lying around and wanted dual subs, so I modified the oem wireless sub to take an additional subwoofer. Dual subs is ALWAYS a desirable setup for HT, so I'd recommend this over replacing the speaker driver. It's really not much more money and you're guaranteed MUCH better end performance. Here's my build:

Items I used:
Dayton Audio Sub-1200

Scosche speaker wire to RCA converter

External Push Connector

I took the woofer out of the oem sub and soldered on an additional pair of wires onto the driver. I drilled a small hole in the sub box and ran these wires to the outside of the box, soldered them onto the external push connector. Secured the push connector on the box and then connected the Schoche adapter, standard RCA cable from the adapter to the Dayton sub. Voila, dual subs. My oem sub is crossed over at 100Hz and I crossed the Dayton at 50Hz for some serious LFE. Testing shows this sub is tuned to about 29Hz and is good down to 20Hz. Substitute any sub you want, but this one is amazing for the $ and I used it instead of my 8" MartinLogan sub because it was just that much better.

Yes, this will void your warranty and probably is beyond the ability of a novice. But it's actually not tough at all and you can expand ANY wireless sub soundbar system with dual-sub theater sound. It is truly night and day difference, totally worth it. Now we have a 5.2 HT system with low profile soundbar, dual subs and real surround speakers. Speaking of which, getting those wireless surround speakers for your bar would be a huge upgrade if you don't already have them. The best faux processed single source (on the bar) surround can't compare to a multi-speaker surround system.