I believe you will want TRS>TRS or TRS>XLR cables for either audio interface. I am using basic 3m TRS > XLR cables that cost under $25 a peice and available from most specialist stores, amazon etc.
For you information I toyed with the focusrite for a while but ended up getting the roland quad capture at a reduced rate, the only reason for my buying decision. I am now putting a Focursrite 6i6 interface in the shopping cart as I want to play around with more mic than I can currently use.
In terms of audiophile DAC's products from Schitt Audio seem to be well reviewed here, not sure about the pricing however.
In terms of audio upgrade with dac's I can plug my adam a7x into my PC with a cable solution and no interface dac, and to my ears there is a difference in quality. The noise floor is audible for a start and the bass extension is poor, but consider this is on board sound card as a source and very revealing pro monitors. Each situation is very different, in terms of PC/laptop, cable's, monitors and indeed room acoustics.