Here's the method and I'll explain below: You'll need a bass rig with some way of connecting the preamp to a mixer input and the poweramp to an aux send or even one of the main outputs, and you definitely need an EQ dedicated to the bass cab output apart from the main EQ. Don't try this if you aren't good with killing feedback with an EQ. What you do is use the bass cab as a monitor/subwoofer on stage. Put kick and bass through it obviously, but also vocals and anything you'd want a monitor for. The location of the cab means you generally can't drive vocal treble hard through it, but you can fill out the stage plenty, and supplement the PA out front. Brighten up the PA speakers a bit to make up for the added stage bleed. What this does is allow you to play bigger rooms with less PA, since the main speakers are essentially just satellites spreading some clarity around instead of doing the heavy lifting. A bass cab isn't a proper substitute for subwoofers, but they reach lower than lightweight PA speakers and it's in the van already anyway, might as well make the most of it. I'm a pro sound tech so this idea started out with putting the kick through my bass rig, then a band touring through a venue I worked insisted on a subwoofer and wedge for a drum monitor and there was no budget for it, so I used my bass cab (SWR Goliath III 4x10) and while at first he was skeptical, he absolutely loved it. The treble dispersion is pretty narrow from the horn, but as a spot monitor it was actually really good, and at 700W and 105dB/1W efficiency it's crazy loud. So now I have a party band (fun covers, i.e. Boston Foreplay/Longtime ) that has a stage volume that vastly exceeds the capabilities of our trusty Peavey PR12's, but with the help of my SWR GIII, we've got all the power in the world. The best part is that it's a very comfortable loud out front because the bright treble is still coming from the PA speakers and not cracking the teeth of folks up front. Even with the rig EQ'ed with vocal feedback in mind, I get a good bass tone and plenty of output, and the guitarists are ecstatic that they can amp up, hear their vocals and know that they're being heard out front, all without lugging or paying for additional PA. I actually like it better than only bass out the cab because I'm better connected to the rest of the band. It's 100% win-win for everyone. But you HAVE to know how to work that bass cab EQ. First you have to get a flat response like a good vocal monitor, then ring out the feedback bigtime. The good news is that you have an excuse to splurge on a great rig, because better bass rigs invariably make better "stage drivers", and are actually cheaper than PA speakers of the same power output and quality. I happen to have the PERFECT rack gear for this, an Ampeg SVP-CL preamp, Alesis DEQ830 digital EQ (8 30-band EQ's in 1RU!), and Peavey IPR1600 poweramp. Fellow sound techs are absolutely freaking out at the power and clarity I get from a dinky old Behringer mixer and this configuration, a ~20lb 4RU rack.