Greetings- We purchased one of those compact JBL EON 210P PAs some years back. The powered mixer conked-out and the repair technician said that the JBL units have a history of problems with unreliability and recommended that we replace the head with something like the one that comes with the Fender Passport. Like the JBL 210, the Passports seem to only come as a package unit (with speakers), plus, my wife would like something that might project subtle nuances with her vocals. We're looking for a powered mixer that will be compatible with the JBL speakers (the old head had an output of 300W, 150w per speaker/stereo). The main purpose it will be used for is my wife's vocal coaching class and rare small/medium cafe performances. The most that we'll ever run through it is 2 vocal mics and a single direct line guitar. Specs we're hoping to achieve: 4-6 channels, basic built-in effects and controls (bass, mid, treble, reverb, etc.), and something with a USB port for running to/from the computer. Any suggestions or recommendations would be GREATLY appreciated :-) Thanks in advance.