Orange Pi would be interesting. The Allwinner H3 at least has an audio codec built in. I think the audio IO is exposed at least on some Orange Pis. Maybe the audio isn’t as good, maybe it is, but I reckon few people could tell the difference. It would save a lot of hassle and money potentially. I know the minimal Orange Pi Zero has exposed line out and microphone pins, but no line in.
Also, how about this for a touch only Zynthian! https://raspad.sunfounder.com/
I have a pledge in for the raspad. but i do not think there would be room in the stock casing for a hifiberry or similar. perhaps if it was mounted via a ribbon cable instead of direct on the pins…
Buy it and get a screen and soundcard to work. 
It already has the screen and soundcard. It’s the DIN MIDI and encoders that will be the hard work!
Ah, you really meant the phone and not the RockPro
Another alternative has popped up in the HardROCK64
Not on sale yet but the pi form factor and proposed $35 start price is appealing.
I’ve taken the plunge on this. Looking forwards to integrating setBFree.
VID_20200727_142954
setBfree on a pinephone. Jack xruns all over the place! Using Mobian for the OS.
That is truly awful! Well done.
The performance is utterly horrid. I’m running 44.1KHz 1024 frames 2 periods and it’s still xrunning. I have qmidinet running to so I don’t have to suffer Jack Keyboard’s 5mm wide keys.
What kind of soundcard are you using ?
[Édit] ok it’s the internal chip of the phone.
Are you otherwise happy with the pinephone ? As a phone ans for other use liké browsing the Web, listening music (without jack server) , sending email or SMS … ?
None of the os’s have full functionality a the moment, ubports lacks account sync and camera, mobian has the camera but no dav support, GoDroid has the account sync but not the phone. It’s pulling together though. Give it a few more months.
Ok, thank you. This sounds like what i’ve read here and there about the pinephone. I was planning to buy me one, but as my very old smartphone decided last week to jump into the sea, I bought another one.
But i’m si borred with Android and all that Google stuff …
6 months it could be very different, or exactly the same, you can never tell with open source!
Zynthian all the things. It can’t be stopped. I have plenty of suggestions for other platforms we can port it to.
And after all, the Zynthian team know it well, its a pleasant thing to port to new platforms…
Here’s anotheone for the bluesky thinking pile. eInk!
Quartz64 is about as fast as a pi4. The audio devices on pine stuff hasn’t been great though.