I got my D100 Pro and here are some issues I've faced regarding the HDMI Arc when using with an LG C2:
The janky hdmi arc connection issue is present, need to power it off (cannot just turn it to standby) and on to connect every time if you change inputs to other than arc to make it connect. And using the TV remote to increase or lower volume, its a separate volume meter on the TV that it's controlling instead of directly changing the dac volume.
However, the biggest issue is: there is a constant noise that's playing from my speaker when hdmi arc is connected, its very audible at listening position (1.5m away) and it is also present when nothing is playing. All other inputs I've tried, usb, optical and coaxial, this does not happen. In fact, I've just been using that audible noise to know when hdmi arc has successfully connected since getting the sound to output from arc is already problematic.
I've reported this issue to AOSHIDA which I bought this from, hopefully it's just my specific unit that has this issue, or maybe it's just the TV model issue. I've stopped using the hdmi arc input completely because of this, previously I've used it for streaming on TV, netflix, prime video etc, I'm now using coaxial instead, there is no noise issue from it, maybe the HDMI ports on the C2 are bad.
Anyone else got this issue of noise from hdmi arc? Is it possible the hdmi arc on the dac doesn't actually go through the usual circuits like the other inputs and isn't actually low noise?
I probably won't be returning this, I'm enjoying the overall sound improvement as compared to my previous dac, current using usb for pc, coaxial for TV streaming and optical for bluray player with no issues (other than the popping noise on usb when playing music that happens whenever sampling rate changes, its mild and I don't mind it). In the first place I got this because I was hoping I could use HDMI instead of coaxial for TV streaming, because previously, I had to change DPLL to max every time to prevent audio dropouts, which happened far to many time when streaming Netflix when DPLL is at minimum and then changing it back to minimum when using usb-pc. I was hoping HDMI arc didn't have that issue, however that don't matter now, I've been using DPLL at minimum all the way and so far zero audio dropouts with coaxial when streaming, haven't touched DPLL at all.