[Mandobart]

IMO, as a former electronics tech and current musician with more than a few years experience playing AE instruments in a variety of bar/club/medium size outdoor venues plugged into a wide variety of amps and PA's - your instrument cord does not make any audible difference. I'm sure there will be disagreements and anecdotal stories/testimonials, but if you're playing a medium sized club through an appropriately sized system you absolutely do not need to waste your money on anything like Monster Cable. IF you are going to run a cord say 50 feet or longer and there will be high power amplifiers and wireless systems causing RF interference then it MIGHT matter. IF you are hitting the road and intend to put some rough use on your gear you'll need high quality cords and knowledge how to repair bad connections. For the gig you describe you can get any instrument cable and it won't matter.

If you have an on-board (or external) preamp make sure you have a fresh battery. If you have no preamp (internal or external) find out exactly what you'll be plugging into. All currently made acoustic amps are designed for an input from piezo pickups. Some PA's have one or two high impedance (HI Z) channels. If you don't know what you're plugging into you should have a preamp or DI. If the place you're playing frequently has acoustic players they should have this. If not you probably know someone you can borrow from.

Are you also singing? Will they provide a mic, cable and stand? I always bring along a trusty SM58 for vocals and an SM57 for instruments if my pickup, preamp, or spare preamp die.