Preamp design approach - Power Supply location

dedicated external power supply is optimal all things being equal

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.

I think that Herman is correct, if you consider shielding as part of the power supply. Most design decisions involve compromise; I expect that is true on this issue as well. Certainly more cost to go to a 2 box solution. Those $ could be used to provide a bigger, better filtered and shielded supply in a one box unit. There are excellent examples of each, for sure.

I also own one of each design...and to be honest...the power supply seems to have marginal effect in my system...more relative is the features...or lack of them...pertaining to the preamps...

The perceived advantage is that getting the transformers away from the line level signals will result in better noise performance, no AC in the preamp box to contaminate the signal. This approach has merit but introduces the possibilty that noise is induced in the system due to the length of wire needed to get the DC to the preamp.

My personal opinion is that the design of the power supply is much more important than where it is located.

having had pre's with both internal and now,external power supplies...a first sound delux with paramount upgrade...i can say that this is so much better then the many others that went before it....i think the design concept is pretty sound...no pun intended!!!

I find the issue quite important as I use a Tom Evans Vibe with the two box Pulse power supply. The background emanating from this set of boxes is exquisitely black and pin-drop quiet. I know the current is filtered multiple times to calm down the erratic swing of the alternating current. This does not assume that single box solutions can't reach the same quality. I do feel that some equipment designers find power supply a more important issue than others.