Topic: Babyface Pro on the go with PinePhone + USB hub + battery + speakers
After over 5 years of owning my Babyface Pro I have finally figured out a practical way to use it outside on battery power. iOS is no option for me. Despite the Babyface Pro being USB audio class compliant, it does not work with whatever Android puts on top of ALSA. I suspect that has something to do the alternate USB configuration which presents only 2 channels for iOS applications, but I have not actually looked into the problem. Anyway, I now have a solution with my PinePhone:
I am using the USB hub that comes with the PinePhone "convergence package" and plugging the Babyface Pro into it. I am plugging the battery into the USB-C Power Delivery port on the hub, which powers both the Babyface Pro and the PinePhone. The PinePhone charges really slowly from the hub, but importantly, it does not drain battery so it can keep playing for a long time.
Unlike many pocket computers nowadays, the PinePhone has a microSD card slot. I have my entire music collection, which is currently 174 GB of FLACs, on a 256 GB microSD card in the PinePhone. I set a fixed mount point for the microSD card in /etc/fstab so music players have a consistent path to scan for music (mounting from Profile or GNOME Files mounts to a different path each time and I'm not sure what determines that path). I have Elisa and Lollypop on my PinePhone. I prefer Elisa, which is what I use on my laptop, but it currently has an annoying bug with one time stuttering a few seconds into the start of tracks, so I am using Lollypop for now. There are several unrelated issues which prevent me from using the PinePhone as my daily driver phone for now, but I have figured out how to make it useful as a portable music player already so it's not just a fun toy.
The speaker is my trusty old Bose Sounddock Portable which is still working well after 10 years. This battery has a 20 V DC output so I can charge the Bose Sounddock Portable directly without needing an inverter and the bulky AC adapter that came with the Bose Sounddock Portable. Its capacity is huge with 266 Wh. I suspect I could use this setup over a whole weekend at a festival without needing to recharge the battery.
This whole setup fits in a normal size backpack and it isn't too heavy.
Notably, there is a faint high pitched ringing sound when everything is connected which goes away if I disconnect the battery from the Bose Sounddock Portable. I do not know what causes that but it is not too bothersome when music is playing. I would appreciate any suggestions to investigate or alleviate that.