Any inverter that advertises a true sine wave output is a good starting point. The others have enormous amounts of harmonics because that's less expensive to build and not a problem for electrical (NOT electronic) tools and appliances. Additional downstream low-pass filtering is always a good idea.
Anything with enough capacity to run a power amplifier will require an automotive capacity battery to provide 120V X 15 A - AKA 1800W or 1 standard AC circuit. A 20A 120V circuit needs to supply 2400W. That's equal to 150-200 Amp/Hours at 12V per hour of operation times the efficiency of the inverter. So, an 800 Amp/Hour deep discharge marine battery might run a good-sized system for an evening before needing a recharge.
Worth it? your call, not mine.