Bill,
A couple questions immediately come to mind. First, how big is the mixer? I couldn't find the size specs on the web page.
Next, where would you place the mixer? It's a flat-pannel type, that will have lots of wires running in and out of it, and you'll probably need some sort of rack or stand for the device.
If you want to downsize for that restaurant job, and you're really tight on space, why not just use a pair of power speakers, plus a small mixer with effects such as the Alesis or Behringer 6-channel models?
If this were the case you could plug your mics directly into the mixer, set the desired effects, then plug the mixer's output directly into the keyboard's auxiliary input, which is also stereo, then output the keyboard directly to the powered speakers. At this point you would have full control of everything right at your fingertips.
Another option would be the Logitech Z-5500 system, which is very compact, and can be used with the same mixer setup described above. It can be set up in very tight spaces and as many will attest, the sound quality is outstanding. I'm not sure if the image below will show up, but if not, you can find the setup at
www.psrtutorial.com then click on music/articles/projects and scroll to the Z-5500 section near the bottom of the page.
Good Luck,
Gary
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Travlin' Easy [This message has been edited by travlin'easy (edited 11-17-2006).]