I am 'zombiebrains' I can't gain access to my new account for some reason so I will try to assist here. I am raw new and just spotted your comments on your E30 issue recently by chance. Although I am aware of the issue for maybe 2 months myself as I too had this dropout sound problem on my own E30 which I bought to use with one of older CD players. In my testing with the available decks I own (had stored away etc), basically all the old CD players have an issue with the newer E30 except
for the 2 Denon CD decks I have (1 of which is an old player) and a Yamaha CDS2000 all work even with a cheap coaxial/optical cable).
I also tested my old Pioneer DVD player and that has an issue but an old basic Sony bluray plays CD's no problem via coaxial into the E30. Funny thing is the player's that work sound better to me on their own rather than the E30, the exception being the bluray thing which is certainly improved by the E30 via it's coaxial input. I decided to keep the device as it sounds great over USB playing content on my PC with foobar and the correct drivers. Also I like it's display. I just wish I had the AKM older version!
Some other information I found here:
As for Amazon, I noticed the following written: Note: Topping Factory does not recommend connecting the E30 to the CD player as the E30 places high demands on the input of the CD player. And on most CD devices, music will stutter / skip.
user review with this sound skipping issue and: https://www.amazon.de/Topping-E30-Stereo-Digital-Audio-Decoder-Koaxialoptik-Fernbedienung-Rot/dp/B08Z7V2W2L/ref=sr_1_8?__mk_de_DE=ÅMÅŽÕÑ&dchild=1&keywords=TOPPING+E30&qid=1630178337&sr=8-8&th=1