I have a GAN1 (modded by TweakAudio.com). For my streaming needs I used a Lumin X1 at one time. That was great but a crazy recommondation.
What I recommend, and what I now use, is a Sonore OpticalRendu + the $500 converter that Small Green Computer sells to take the USB output of my Optical Rendu and then outputs SPDIF to the GAN1.
I use ROON and both the Lumin X1 and Sonore OpticalRendu are ROON READY. Volume is done by ROON for the OpticalRendu. I used the LeedH volume when I had the Lumin X1. Both are great choices.
I recently bought a used opticalREndu for $700.
BTW - after I got the mods ($500) I sold a lot of gear that was no longer needed.
BTW2 - I posted how to do all of this streaming on the GAN1 thread from earlier in the year. The Lumin X1 was a bit trickier, and I had to talk to Lumin of the setting to use.