I'm about to completely renovate the house so will be installing new electrical and data cabling everywhere. I'm looking at installing multiroom audio for 5 to 9 rooms. I have no pre-existing hi-fi equipment and am not an audiophile but want a system that will be discreet, decent quality and attractive to any future purchasers of the house. All my data cabling, router, NAS network switches (including PoE) will be upstairs in a cupboard at the top of the 3-storey house. As I understand it, I could either a) group all my players and the server on Raspberry PIs with HifiBerry Amp2s in the upstairs cupboard and run audio cable (between 7 and 20 metres) to the passive speakers which I want to place in the ceilings and walls, depending which has most space to accommodate them or b) have just the server up stairs in the network cabinet and run CAT 6a data cables to the players placed next to the speakers in each room. I intend to control the system using smartphone apps over wi-fi, and perhaps some touch screens/tablets in the future.
My main question is: what to do about the power supply? The centralised solution a) is neater and perhaps cheaper and needs much less work than hiding transformers and RPIs behind walls and running power wiring as well as data cables (unless PoE+ was a solution). However, what kind of transformer can I use in the "data cupboard" which will serve ALL my RPIs (i.e. just one transformer for ALL the RPIs)? And would it affect the audio quality badly. On the other hand, if I use solution B, would running 16 gauge speaker wire for up to 20m affect the audio quality badly?
Any other comments on the pros and cons of either setup would be appreciated: