Both stereo and mono miniplugs work fine. I'm actually controlling two items from my 950 via a miniplug y-adapter and one uses a mono mini and the other uses a stereo mini (what I had lying around) with absolutely no problem.
As long as the voltage gets through it works and stereo/mono makes no difference.
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RAF My HT (latest update 03/23/02) Now includes Outlaw 950 and Outlaw 755 [This message has been edited by Robert A Fowkes (edited April 30, 2002).]