Sean, I think that some manufacturers started out as either pre or amp "specialists". Given their original "killer" product, they then set out to pair it accordingly... which is fine but, it seems that the mechanics invlolved in casing pre's vs. amps (damping, shielding, emi filtering, etc), let alone the electronic circuitry design & choice of components -- is a herculean task, maybe, when it comes to voicing components alike?
I'm suggesting that although we DO get some up-front taste the brand is connected to (example: Symphonic-line - "fast & dynamic"), with some up-market pre-power pairs certain subtle characteristics we have connected to one or the other component seem absent...
Now, if we tweak one or the other component, MAYBE... but why have to tweak?
Cheers