Hello every one. I'm Hailin Huang, sales manager of TOPPING. I have engineering background for many years so I think I may be the suitable person in our company to communicate directly with you.
Sorry for our late reply, because our response comes too late, that makes every one here feel confused and also make Amir questioned.
I would like to introduce the problem of "click" here. And if any one have other questions, you can ask me here.
What makes the click? Is it a defect unit?
AK4493 will output a pop noise when the sampling rate changes, especially in DSD. To void this noise, we test many method including semiconductor switch and relay, at last we decide to add a relay because it did better in avoiding the pop noise. But the relay also bring the click noise. You can hear the click from the DX3 Pro itself, and also a little from the headphone(If the sensitivity of headphone is high). Because this is our setting, so every DX3 Pro has click sound, the unit with click sound is not a defect unit.
When it will click?
The relay is controlled by both XU208 and AK4118. When there's a audio stream, the relay closed, and if there's not a audio stream, the relay cut the output. So if you continue listening to music, you will not hear the relay so often. But if you doing normal operation to your PC withoud a continuous audio stream, the relay will works very often.
But when the sampling rate did not change, the relay also keep working.
Yes, that's because we are not able to judge the sampling rate is same or change when the stream comes, so we cut every time when the stream over and on.
Is there a solution?
I think yes. We will try to find a solution from XMOS. If it did not send out "cut off" signal when sampling rate did not change, this will be able to reduce most of the click sound. We already ask the XMOS firmware supplier try to solve this problem, this will take serval days and we will tell progress and results if necessary. I think the best solution will be a firmware update for DX3 Pro, we will keep working on this.