Hey, thanks for the quick response! I hope the Faire is great.
So I’ve been playing around with my Zero. Namely using different PSUs on different power rings within the house, and I just think that the pHAT DAC is quite sensitive to fluctuations which results in some interesting and at times bizarre noise from the line out. I’ve ordered some high quality usb cables and 3.5mm jacks, all in an attempt at shielding the signals from the speakers. I’m using quite high spec amps and speakers in my set-up and I think they are generally quite receptive to the hissing and bleeping the DAC emits. Disabling audio dither also helped a little.
RE the high CPU loads and SD Read loads - I reinstalled my Zero with Jesse Lite (Don’t know why I din’t do that in the first place… N.B. I had some real issued trying to get WiFi to work with wpa_supplicant. My Zero REALLY didn’t like the idea of DHCP. Had to revert to static, which i kind of don’t like for some reason) and it has helped a great deal. I still get quite a bit of jitter from time to time, but I suspect this is now a networking issue rather than a Zero issue, although my Pi3 seems to be able to deal with networks better. And, as you say, I’m sure it is also due to limitations within the shairport-sync application.
I’m still wondering whether this is a soldering issue. I can’t see any blemishes - I’m rather proud of myself for a first try actually! - but I know from other sources that soldering ground pins can be a little tricky, and I’m wondering if they’re not soldered correctly it can cause a little bit of extra ground interference through line out? That may be totally stupid and completely nonsensical. I’m afraid I don’t have much experience with hardware and hacks etc. The Pi is my first venture in to this kind of stuff!
Lots of love,
EDIT: Also I should mention that this Pi is dedicated solely as an Airplay receiver. The only other thing it ever does is accept SSH connections. Surely it has enough processing power to manage this without interrupt?