Source: personal testing on two phones.
I prefer wired IEMs, and have been using a Truthear Shio USB DAC with pleasure on my P7 for much of this year. Plugging it into my P8p or my wife’s p8 results in LOUD static in the left channel only, and virtually nothing else. Maybe hints of what’s actually supposed to be playing, but I’m not tough enough to suffer a listen.
It doesn’t appear to be a well-publicized problem. I found one meagre reddit post where someone with a similar, Tanchjim Space USB DAC had what appears to be the same thing. Also, one other on Crinacle’s discord.
I have a simple dongle/adapter, with a cx31993 chipset in it. It seems to work fine with the P8p; no static. I will conduct more testing with cheap dongles, but I have only the one expensive one (the Shio). Your testing and comments are welcome.
True in technicality, but in practice—at least for Truthear—the firmware update changes functionality (and you can swap back) but doesn’t actually “update” anything. And no, they haven’t released any new firmware in a while, let alone since the P8 launch.