Powering part (or most) of a circuit?

[nicbul]

I have a couple channels from a Yamaha m1516 mixing console and I would like to power them up, do some signal tracing, and see how something like this works. 

The board is supplied by +/-25V, +10V(led indication), and +48V(phantom power).  I would be powering it with a dual bench PSU.

Is it generally safe to power the board solely with +/-25V to test the signal path?http://cloud.tapatalk.com/s/5a485924ba3d6/yamaha_m1516.pdf

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