It def will be diminished if you have a lesser preamp that drags it down.
The deal with DACs is that it all matters. Not just DAC chip or how it is implemented but the power supplies, the critical output stage, the filers, volume control (if it has one), quality of the the case, the vibration control, the entire package. A great way to tell the strength of a DAC is how it sounds by itself. It takes more possible synergy problems out of the equation when evaluating it.
Like you in my system I thought the DSD sounds much better with a Pre and with the M1 I prefer without a pre or at least it is good enough to chose the different flavors verse of with or without vs a obvious sound quality jump. That right there kind of says it all. Are there certain DACs that have great synergy matches with certain pre's? I am sure there are but chances are if a DAC sound good enough without a pre that advancement in the output stage matters and it will carry over to the performance with a pre with the caveat of synergy concerns aside...
All this said I agree with your point that prob a big part of the reason the Bricasti has such superior sound quality is because of it's dual mono design; with duel completely isolated channels, each with its own dedicated linear power supplies
because of its outstanding duel mono output stage.