I have had the DAC for a about a week, using it with a squeezebox duet and my pioneer elite 05 dvd/cd player as a transport (thinking of getting something better as transport but not sure if that will be any better than pioneer). I have a new Cary 120s tube amp and using a calypso preamp from my dealer until my lector tube preamp comes in. I wrote Music Hall about break in time and Roy Hall wrote back telling me it takes a couple of days but recommended an EAT tube damper that makes a nice improvement. I put that on but never listened to the unit without it so cant compare. Plus I read an internet posting from somebody that compared a bunch of tube dampers and thought the EAT damper sucks. However, it may be tube/unit specific for the kind of improvement you hear. So far, (i am still on the first 50 hrs of amp break in) i think the music hall sounds very good, but not as good as my vinyl on a rega p3/24. That was why i was wondering about the mod. Affordable audio says i can come in an do an A/B comparison since i live in LA area. i want to slowly tweak the system but hate wasting money on stuff that makes imaginary improvements (i have not bought any high end IC or speaker cables yet).