What's most important synergy wise???

I agree about the weakest link argument, but I don't think that in this case, the source to pre link is going to be a weak one whichever approach is taken - I don't think there will be a "synergy" issue; but one pre may be sound better to the listener than the other based on personal preference.

Lapierre:

I'm running Straight Wire Serenade biwired into B&W N803S.

Yes, I agree the VK-52SE is an awesome piece but the C500 is McIntoshs least expensive fully balanced preamp and priced to compete with the BAT.

decisions, decisions...

As above... what sounds good to one listener is just that ,
a personal preference . I don't equate that with synergy .

Synergy is about components that work well together . Whether one prefers the sound or not !

You wouldn't put a 3 watt SET amp with speakers having a wide impedance curve rated at 80db. And you wouldn't put a preamp with a 1k ohm output rating driving an amp with a 2k ohm input rating and so on . While you may get them to sound good to someone , with the right circumstances , it would not be a synergistic match .

Know talent ; you are worrying about the right stuff , just alter your priorities . It all matters , just to varying degrees . I still believe that the amp>speaker synergy is paramount with the preamp>amp coming in second .

Donning flame retardent suit !

Good luck .

Saki70, totally agree with your "synergy" hierarchy. I think the source>pre is not much of a synergy; only if your using low-gain cartridges is it much of an issue. I would choose the pre without too much ragard to the digital source in this case (from a "synergy" perspective).

From my experience-

Speakers>Amp
then the best source you can afford with preamp that will not
get in the way of music and that is also as transparent as possible but if it can add that special sparkle, magic......even better. Of course it has to be matched with amp's input rating.