I do, and it's wonderful, but I think that "sub out" may be misunderstood my many. The extra 2 outputs can be designated to ANY instrument/sound/element that you choose. It's not a dedicated sub out, although you CAN set it that way. A great way to use this would be:
1) route the vocals thru the extra outs to give an isolated monitor option ... or
2) route bass/drums to a separate channel of your mixer for precise low end EQ enhancement without muddying up vocals and lead sounds

I bought this Fishman Subwoofer:

https://www.sweetwater.com/store/detail/SASub--fishman-sa-sub-300w-subwoofer-for-the-sa330x