Interconnects - better before preamp or after preamp?

I wouldn't worry about it.

The signal is as good as it gets AFTER it leaves the source.

Keeping with audiophool philosophy-wouldn't it make sense to attempt in keeping it that way at least to the preamp? 

How does a "better" cable improve it after the pre? Must be nothing more than a tone control and wallet depletion device.

Op, you’re going to get responses all over the map. Do yourself a favor and figure out for yourself what works best in your system. Find a company that has cables you are interested in and have a return policy, buy 2 of the same cables and put them in your system before and after, listen and assess. Then swap in your lower end cable before, listen and assess; and likewise after. Your system, your ears, your assessment, return one better cable if you don’t think it matters to have 2 better cables on both ends. Easy peasy

Personally I'd get the best and use the same from source to pre and then pre to amp(s).

@noromance +1 — IME the interconnects that make the most difference are closer to the source.  I used to use silver interconnects from my DAC to preamp and then copper from my pre to the amp.  Didn’t work nearly as well the other way ‘round.