Hello. Long time lurker, first time post. I am having a hard time with my I2S connection between the PO100Pro and Topping D90. Based on the I2S interface in the manual, I should be in Mode 2 on the PO100Pro and STD on the D90. But I am not getting any sound. Optical and Coaxial is working. Any troubleshooting tips to get the I2S connection working? Thanks in advance.
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Sorry for the late reply (been a lurker here, but only recently created an account).
I recently acquired almost the same combination of gear, the Topping D90SE and the S.M.S.L. PO100 Pro, connected through I2S. I chose that combination because the USB connection on the D90SE is already in use for another source and the PO100 Pro got good reviews (for a 5th of the price of other solutions).
Initially, I had this same problem: No sound through the I2S connection, while coax does work just fine. I found a reference on the Internet that disabling pin 16 would help:
https://audiophilestyle.com/forums/topic/67506-ddc-i2s-dac-no-sound/
I grabbed a cheap HDMI cable and bent pin 16 inside using a needle and that did indeed do the trick!
All other settings are left to defaults, for the PO100: I2S Mode 2, UAC 2, for the D90SE: IIS Phase STD, IIS DSDR LRCLK, DSD Flag 15.
The fact that disabling pin 16 apparently unmutes the channel seems to imply that Topping expects a high signal to mean Mute, while S.M.S.L. seems to expect a low signal for the same and sends a high to unmute. Or perhaps there's another reason? Some missing signal to the PO100 that tells it it can unmute?
Due to the lack of standardisation of the I2S protocol through HDMI cables, it's hard to point fingers, but if my theory is correct then I tend to side with Topping here.
If we want a proper solution to this problem, I think contacting Topping has the best chance of succes: I doubt the PO100 could be updated with newer firmware, while that is an option for the D90 range...