Roland68
Major Contributor
That sounds like a grounding problem, unfortunately an extremely complex one.There would be no way to test whether any pop occurs with just the amp plugged in, and nothing else connected because you've removed the ability to play any audio through the amplifier. This is not a case of random pops happening while the amp is sitting idle, which is why it is not a grounding issue.
The pops occur when audio is paused (i.e. when playing music from my Mac's Music app -- it probably also occurs if I were to trigger a system notification sound, or paused a YouTube video). And it's two pops, about 0.5 to 1s after the audio has stopped -- consistently, every time. I also want to stress, again, that this does not happen with any other power amplifier I've used in the same system with the same cables, same connection chain, etc...
Edit: I've attached a link to an audio file to demonstrate the issue... please let me know if there are any issues accessing the file.
At 3 seconds, you will hear the first mouse click starting the audio, at 16 seconds, you will hear the second mouse click pausing the audio, and shortly after you will hear two pops.
Edit 2:
So I have gone through a variety of different tests, and this was the results:
- I disabled auto sensing on the A7: same results (two pops after pausing)
- I then connected the A7 directly to a different DAC -- the Topping E50 -- via TRS: same results
- I then connected the A7 to the E50 with different balanced cables (TRS to XLR), slightly different results: One audible pop after pausing sitting 2 feet away (I did not listen with my ears any closer, but I bet there was a second pop that wasn't as audible)
- I then connected the A7 to the E50 via RCA: no audible pops sitting 2 feet away**
- I then reconnected the A7 to the regular chain (D50 III to L50 HPA to A7, all via TRS), and changed the output level on the D50 III from 5v to 4v: same results (two pops after pausing)
- I then connected the A7 directly to the D50 III DAC via RCA: no audible pops sitting two feet away**
** no audible pops when 2 feet away, but there was the faintest of ticks when I had my ear within 3 inches of the speakers. And honestly, if that was the result with the balanced connection, I wouldn't actually care because the tick with the RCA connection is so minuscule that sitting at my normal distance, it wouldn't have even been noticed.
I performed all of the same tests above with my Topping PA5 II amplifier, and there wasn't the slightest pop, tick, etc...
Sadly, based on all of this, I must come to the conclusion that the A7 amplifier needs to be returned. Another thing I discovered is that when connected via RCA, the RCA gain switch on the back of the amplifier does absolutely nothing. There is no change in the gain level switching from L to H (Low to High). I don't know if it's defective, or if that's normal functionality?
I would still like to heara responsefeedback from @3eaudio on this.
If you've turned off automatic detection, the popping can't actually be coming directly from the A7 anymore, but is just being amplified by it.
What's your source, and how is it connected to the DAC?
Could you try connecting via Bluetooth with one of the DACs?