Placement of components in audio rack

I isolate the digital from the analogue to avoid EMI/RFI contamination. I also like to keep equipment with large power transformers away from more sensitive equipment.

Power amps on the floor between the speakers. CD and DAC players on a separate rack. Pre-amp, phono pre-amp and turntable on a separate rack.

I think you will probably lose any performance you gain by playing with component positioning on shelves ,if you have to go to longer interconnects. From my experience, shorter ICs always have equated to better sound. Even inferior shorter ICs sounded better than longer run(2m or greater)better quality cables. Good idea about running the tuner as far away from the rest as possible. Not sure you need to goto the extreme of a different room. Unshielded interconnects will be an issue, however.

I believe the length of the IC and sound quality is related to the IC's being balanced and the output impedance of the pre-amp.