Squeezebox Touch Hardware Mods
I've been running squeezeboxes for a good few years now and I still own and original SB and modified SB3(blog here). I've always been interested in the Transporter but I don't think it would be any better than the modified touch I'm using now.
Like most of these things, the place to start is at the wall wart switched mode power supply. These are used as they can be made very cheaply and can effortlessly provide higher current requirements.
Having experienced excellent results with over specified linear power supplies and my own low noise voltage regulator in various applications including the SB3 this is where I started.
50VA toroidal transformer, Hexfred high speed diodes and 2 x 22,000uF Panasonic TSUP capacitors provide approve 11v DC unregulated which can provide in excess of 5A. Ultimately, the Touch will need a few power supply rails. The main 5v regulated rail and an unregulated rail to feed the clocks and new internal regulators.
Initially, the power supply with its low noise 5v regulator can supply the whole Touch in place of the original wall wart PSU