Intermittent pops / read-like errors with Shanling ET3 + Topping DX5 II. Looking for technical insight

[zreenco]

Hi all,
I’d appreciate some technically grounded opinions on an issue I recently ran into.
I bought a Shanling ET3 CD transport and paired it with a Topping DX5 II DAC. Connection was tested via coaxial S/PDIF and later optical (TOSLINK). The DAC is connected to headphones only (no speakers), and the system is otherwise very simple. During CD playback I experienced intermittent, random audible pops/clicks. Not track skips or repeatable errors, more like brief, single-sample glitches. They were rare but clearly audible and not repeatable at the same position. They would happen roughly 2-3 times in the span of an album length. I've used brand new cds right out of shrink-wrap. The transport and dac were on an extremely sturdy komoda, and I've nudged her and did get a skipping from the ET3 and it was an entirely different sound from what I was experiencing.

So I tried, coax, optical, different CDs (I have huge collection), different power outlets, no nearby interferance etc. The behavior persisted across all outputs.
The seller suggested this could be a clocking / compatibility issue on the DAC side, and recommended USB or AES/EBU, or even adding a DDC to “clean” the signal. That explanation didn’t fully convince me, since S/PDIF into a modern DAC should not produce random pops under normal conditions (at least I feel like it should not).
In the end I returned the unit (within EU withdrawal period) without testing anything anymore, but I’m still curious about the possible root cause, especially since others report the ET3 working fine.
My questions:

1. From a measurement/engineering standpoint, what realistically causes random single pops like this in a CD transport → DAC chain?
2. Is a transport–DAC “incompatibility” via S/PDIF actually plausible here, or is that more of a hand-wavy explanation?
3. Would USB truly avoid such issues, or just mask them with more buffering?

I’m not trying to bash the product, just trying to understand what this points to. In the end I still want a cd player. I really want to get off of streaming and simply turn off my computer and my phone at the end of the workday. I'm looking at mid-range Rotels, Marantzes etc. I am a bit nervous though, is the choice of going the "transport route" something that includes buying other hi-fi gear just to get a reliable perfect playback (no pops and clicks)? I really don't want to spend money on things just to get an error free cd playback.

Thanks in advance.

 

[Morla]

But did you actually try usb from shanling into the topping?

 

[zreenco]

But did you actually try usb from shanling into the toping?

Hi. Nope, I was nervous. They said "you cannot return it, you used it too much"... they got me paranoid and tried to write this as a warranty claim in case they decide there is a fault. Since I didn't have a usb cable required, I just decided to pack it up and push for a 14 days return period.

 

[Morla]

In the big dx5 II thread ppl reported "issues" using spdif which.. may or may not have disappeared after firmware update(s).

 

[zreenco]

In the big dx5 II thread ppl reported "issues" using spdif which.. may or may not have disappeared after firmware update(s).

Ok, that's something to look into, thank you.

EDIT: Saw a few experiences with Topping s/pdif, but it is nothing like mine. Also, mine sees the same issues when connected over toslink.