I have experience in my system with both internal (cj 16LS, ARC Ref 2, Hovland HP-100, Lamm LL2) and external power supply pre-amps (A.I. Modulus 3A, Cary SLP-98P, and First Sound 4.0 w Paramount Plus upgrade).
While it is difficult to say what each pre-amp would sound like with the opposite power supply approach (don't have access to their prototypes--if they ever existed), I come down on the side of external P.S's.
I don't care for the extra chassis and connecting cord, etc. hanging around, but I am more willing to accommodate them than not.