@TP-Wong , more testing of the D50 today using slightly different hardware.
Setup: Connected to D50's Coax port using
Singxer SU-1 as DDC, see picture below. Both USB & Coax cables are different from prev test.
Tested using both Windows standard test of a sound device as well as REW's Generator.
Result: With this setup beep comes out thru the D50 using Coax input and Windows std test of sound devices.
Using REW's Generator sending Pink Noise to D50's Right channel turns it off after ~ 3-5 secs. Left channel works fine.
Conclusion: There's two issues with the Topping D50:
1. Implementation of the Right channel DAC/Port.
2. Implementation of the Coax Port. Seems to be shaky, does not work with iFi iDAC2 as DDC but works with Singxer SU-1 except the Pink Noise which does not work for the Right channel in any configuration.
Edit: Third report sent in to Topping, still no response!