I changed only because the stock cable broke after the warranty expired. I have had good experience with gold+silver cables for my HD650 so I thought that would be a good idea for the T5p. The A1 is a great amplifier. Good luck with the A1 + T5p combo. I am sure you will love it.
I do not have a lot of experience with cables and interconnects. I always buy cables based on how they feel and look. How flexible they are and if they are heavy or light. If I should give one recommendation for a cheap USB DAC in the EU which sounds VERY good and will probably be my next DAC. You should have a look at: http://www.henryaudio.de
I do not know the USB RME babyface or the ADAT. But Henry Audio --> A1 --> T5p would be a killer combo.