Hi,
I have an MB6582 with 4x8580 and 4x6581, and I got myself a stereo noise gate by building two MXR guitar pedal noise gate clones following the schematics on tagboardeffects (I built the stock version with the three changes mentioned in the very beginning) and boxing them up with a dual pot.
(UPDATE: If you build this, I advise to use 2N5485 instead of 2N5952 as transistor Q3, as it gives clearly better results. I built a second stereo unit of these today (24.7.2014), and went with