If you read my posts carefully, you will note that A20a v1 does not have the USB noise problem, and A20a v2 does. Which means the problem is precisely related to this amp.
Anyway, I tried some tricks you suggested earlier, and the results are indeed surprising. I was actually amazed.
All...
Well...
I glued over the + inside the cable plug with an electrical tape and the DAC was not detected by the PC.
Then I tried that with the -/ground and this time DAC was detected AND THE USB NOISE IS GONE! SICK!
Well, obviously the problem is how the A20a v2 handles the noise from the PC carried over the USB cable and TOSLINK would remove it, but it is not an option.
I just tested the silly AudioQuest JitterBug and naturally it did absolutely nothing but maybe slightly changed the pitch of the noise...
I don't think we are talking about the same thing.
The noise I am talking about - when computer is plugged into DAC - was not there in A20a v1 but is present in A20a v2.
I got another A20a from the same seller (amazon.de). This time it is the updated version.
The differences:
- no relay clicking
- higher power draw. It consumes 2W more power (idle: 3W vs 1W, music: 6W vs 4W).
- a sticker with a serial number underneath
- the previous A20 had an extra hole on...
Do you know what means what in a serial number? What designates the newer, fixed version?
Paying an extra 100euro for a PSU to fix a brand you 180euro AMP just to make it right is not my idea of a good deal :/
So the coil whine is because of excessive (3W) power draw from Sabaj 5V output?
I wish there was a way to disable the headphone amp on DX3 Pro+, as I will never use it.
The A20a I bought was from Amazon.de and was purchased 3 weeks ago - so it should be the new edition, but of course there are...
I did some testing with USB input and Auto Standby. The DAC will turn on from Standby ONLY if the sequence of events is like so:
Plugged into the power socket -> DAC goes to standby -> USB-connected device is powered ON (or the usb cable is re-connected). It will stay in standby and not turn ON...
I got Sabaj A20a and it paired beautifully with Topping D30 (which draws 3W 15V when on), powering it from its own internal PSU with included cable. Sound was clear and background was silent.
However, I just got DX3 Pro+ (draws 6W 15V when on), and it causes the Sabaj PSU to coil-whine when DAC...
Can someone tell me if when D50s is ON and the power is cut to it (plug is pulled out of the socket) and then it is turned back on, does it return to being ON, or defaults to Standby?
If the latter, then does it turn back on automatically if it gets signal through USB?
Also, on a separate note...
Can someone tell me if M200 is ON and the power is cut to it (plug is pulled out of the socket) and then it is turned back on, does it return to being on, or defaults to Standby?
If the latter, then does it turn back on automatically if it gets signal through USB?
Also, on a separate note - has...
I just got DX3 Pro+ and found out it has a serious flaw for my application. I have home automation that kills the power to my audio system when I leave home. It turns it back when I return. However, when power returns, DX3Pro+ does not return to the ON mode, it stays in Standby and it does not...