I'm going thru the exact same thing. My amp does have its own manual volume control so I can use the DAC but after getting used to remote volume control on my previous DAC I'm also looking for a different solution.
I tried a Schitt SAGA and it didn't work for me. It turned down the volume OK but sucked all the life out of the music. I can also choose to use Foobar2000 with it's software volume control which my not sound quite as good as AlbumPLayer but it is much better than the SAGA.
I'm not a ROON user but depending on the USB driver it may not work.
My DAC manufacture recommended the Khozmo passive that can be purchased for under a grand (way under depending on the resister type)