FWIW, for those who have an acoustic guitar amp with XLR line outs, I pulled an old active subwoofer, a 100w Infinity BU-80 from my closet that was for my old sound system. It was destined for Goodwill. But I  figured what the heck, I got a XLR to RCA cable, hooked it up to a line out on my Boss Singer Live and I tuned the frequency to get the bottom I was missing and I discovered that it really fills out my bass response for the price of a $16 cable. I looked and you can find decent used active stereo consumer ones for under $100. Beats spending hundreds of dollars for the usual dedicated active commercial PA subwoofers if you are using it for mostly home use. This really helps for acoustic amps with smaller speakers.