The Akai VX600 is a very nice synthesizer. It's got 12 analog vco's, 6 independent multitimbral voices with individual outputs and its matrix has an input for voltage control. In other words: it's extremely flexible and useful in an analog setup. The fm is also very nice. It has some negative sides too: personally i'm not very impressed by the envelopes and the lfo's, there's a horrible bleep coming from the backlight and the filter can sound like a tin can occasionally.
Also the display can get a bit unreadable after years of use but fortunately Wolfgang at midi-rakete.de has a great solution for that: a fresh EL-Foil. It's very easy to replace. I couldn't find any pictures so i shot a few for other VX600 owners. Here's more VX600 info.
EL-Foil replacement
EL-Foil in the mail
open up
the display
get out the display
slide out the old el-foil
a bit of soldering
slide in the new one
ready