I tried that for a while in my last car (Mitsubishi Galant) and I would occasionally see my empeg bounce into standby, and then back on. Running the memory power wire directly to the battery solved it (fusing it of course!) I'd say try it, and if you see it drop into standby mode, run to the battery directly. I still kept the switched & ground into the harness with no problems.
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-Michael

#040103696 on a shelf
Mk2a - 90 GB - Red - Illuminated buttons