120V or 240V

I think you are proceeding correctly with the 120V version, for the reasons stated by the others who advocated doing that.

The only technical differences I can envision that would result from running on 240V are:

1)Less current would flow in the power wiring, the ac fuse and switch, and the primary of the power transformer. I would expect any sonic differences resulting from that to be subtle and unpredictable at most, and not necessarily in the direction of being better.

2)You would be exposing the ac input of the amps to noise or distortion that may be present unequally on both 120V phases, instead of what may be present on just one phase. That difference should be minimal since the 240V wiring you would be using is a dedicated run. But to the extent that there were any differences, they would probably be in the direction of making 120V operation preferable.

Re the dealer and others claiming that 240V is preferable, I question whether those claims are based on extensive and carefully controlled comparisons that eliminated other possible variables.

Regards,
-- Al

A third possible difference, that I should have included in my previous post:

3)Leakage currents between the ac input and chassis/circuit ground in the amp, that might flow through parasitic capacitances or resistances in the power transformer, would be greater with 240V applied than with 120V. I would expect those currents to most likely be insignificant, but if there were any significance it would be in the direction of favoring 120V.

-- Al

Good point, Jim, and that does seem conceivable to me, especially if the interconnects to this amp are single-ended (I don't know if they are single-ended or balanced).

With the amps running off of 240V, both sides of the primary of the power transformer in each amp would be 120V removed from chassis and circuit ground, conceivably increasing the degree to which leakage currents would tend to affect chassis potential, at least at noise frequencies and perhaps at hum frequencies as well. And with the preamp powered by 120V, the ac safety ground wiring would be unlikely to be effective at keeping the amp and preamp chassis at the same potential, because the inductance and resistance of the run between each component and the electrical panel is in that path. So the likelihood of inter-chassis noise currents flowing through the interconnect shields would seem to be increased.

So of the several factors we've identified that could conceivably result in sonic differences between the 120V and 240V versions, the majority of them point in the direction of the 120V version sounding better. Not that that means too much, of course; the only way to judge would be via carefully controlled listening comparisons.

Best regards,
-- Al