I don't know if anyone has done this comparison. Seems to me that if you don't need the DAC (or it's not as good as what you already have), you are plowing a lot of the sticker price for the DAC in the Grace, where the HR-2 all your $$ goes into the amp itself. Admittedly, that doesn't insure that you would like the HR-2 better, but it is a consideration I would think.
What does the rest of your system look like (source/cables/cans)?
Mark