I am sorry but these two DACs have nothing in common other than both are NOS type converters. Trust me, the Adagio in combination with my HPA-21 was the best sounding set-up I have ever experienced in my home!
But I will give the DAC-21 a fair chance to shine, I have just contacted the Bakoon distributor in Germany to lent me one unit in early Aug, I will report back.
I will soon report back, I have just managed to get hold of the DAC-21 to be shipped over to my home on Saturday.
Have you tried the BNC type 'Satire link' analog-out cables yet? I am wondering which ones to buy.