While not exclusively an acoustic instrument amp -- a phantom-power-armed Neutrik combo jack accepts both 1/4" and XLR inputs -- the new SWR Spellbinder Blue is the perfect combo for the gigging upright bassist. As you can see in this video, the S.B. is not only compact, it's extremely light, meaning you'll be saving both space and your back. Not that you care about that; I mean, you've chosen to play the upright bass, after all.