Finally, someone with my same exact question!! Now if only Gonk would respond and tell us if the 990 DAC's are up to par with the burr-brown in my Denon and your Adcom

Actually assid, the DAC used in the 990 is the Analog Devices 1852 and it's specs can be found here:
http://www.analog.com/UploadedFiles/Data_Sheets/536821559AD1852_0.pdf

Perhaps you could scan through there and compare the specs to the DACs in your Adcom. I'd love to hear what you find out.