My friend asked me to make him a rack unit containing a Sansamp bass preamp (my choice is BD21 lite, and a good compressor (like a THAT4301 based one). Since it's going to be a rack unit I can power the preamp from something bigger than 9V battery. However, problem is that THAT compressors use +/-12V supplies, and the Bass Driver uses single-rail supply. What's the best option of connecting them? Should I simply power the preamp from one rail of a dual-rail supply? (I suppose not, because of difference between loads on both rails). Or do I have to make 2 separate power supplies?
Also, what's the best (most usual) option to choose - compressor before preamp, after, or switchable order?