Hi Hartmut,
Don't hold your breath. Standard clocks in the U2 do not require burning. Pretty stable from the beginning.
There are reports of a good sound quality coming out D10 converter, perhaps comparable to U2. Having spare D10 in a drawer i not a bad things. But D10 comes with standard oscilators. If you want something better in sound quality, good clocks on U2Pro will do. Get pro version due to the S/PDIF transformer and external power supply connector.
I thought someone mentioned a 500 hours burn-in period in this thread also for standard versions. Not sure if that is true… So what is your experience with the upgraded versions regarding burn-in process?
I bought both and returned the Topping. It's been a bit, so I can't recall exactly why I preferred the Douk, only that it sounded better to me. My setup is atypical, since I'm using (1) using the optical output and (2) piping it into my Chord Hugo 2, which is generally jitter resistant but has no galvanic isolation. I also use linear power module with the Douk, which isn't an option for the Topping.
Burning my upgraded U2Pro was interrupted by scheduled country-wide power blackouts every 6 or 4 hours that started one year ago. But during first few weeks I noticed improvements. It was not so dramatic as after upgrading Amanero module in my R2R-11. I guess there is a cleaner power inside R2R-11. Perhaps to get similar results it would need to replace on-board regulator with low-noise version and get linear PSU. Crystek oscilators are sensitive to the psu noise.
Try a battery bank if it needs 5v? Lipo04 is best for current delivery and sound.
The other function of U2Pro is redirecting ground loops. Battery bank doesn't do if disconnected from mains. LPS is other suggestion. Try both, it is never known what is a major problem in your system.
I’m not trying to solve an issue, just looking for a power supply with the small barrel plug that fits this unit. I can’t determine if Douk sells one.
U2Pro comes with short cable, barrel plug on one end to plug to the U2Pro, USB Type A on another. It makes it compatible with any USB charger adapter, there are many to chose from. Hope it helps.
