Transport Selection on Headphone Setup


I'm building a headphone system. I have Senn600s, and I'm planning to build a Nixon TubeDac and either a Waarde or Ciuffoli headphone amp (from schematics on the Headwize project library).

I have a few questions:
*Anyone have a similar system? Love it or hate it? Anything you wish you'd done differently? Suggestions on which head amp to build?
*Eventually, I'm planning on setting up a Phillips cdpro 2M. But that's a bit of work, and it might take me a while before I can get around it. Until I do, I want a cheap transport to use with the above system. A friend advised me to look for something under $50 on Ebay with a digital out. Is this a bad idea? Anything I should watch out for if I go this route?

Thanks for your help.