Component Placement

Monos beside speakers. Longer interconnects.

If possible I would place source and pre on stand to one side of listening position, and, as noromance stated, the mono amps by the speakers. No soundstage interference around your speakers.

+1 noromance, and mesch.
If you can run balanced interconnects, then longer distances between the preamp and source are minimized.
Using sound dampeners or isolation under your components would also be a good idea.
My amps are on Sound Anchor Stands. Under each amp are either Herbie's Fat Dots or Stillpoints. Same with Preamp and DAC.
B