SENGA

Hi SENGA,
 
For 1., there should be no extra setup for the kernel config change. `g_audio/UAC1` gadget config should be enough (no need to recompile the kernel). The thing you need to change is the alsaloop daemon (this line). I did not verify it, but AI gives a example of looping the speaker and microphone in 2 different threads like this:
 
alsaloop -v \ -T 1 -C hw:Loopback,1,0 -P hw:CARD=B,DEV=0 -t 20000 -A 3 \ -T 2 -C hw:CARD=B,DEV=0 -P hw:Loopback,1,1 -t 20000 -A 3  
. It looks legitimate, you can give it a try.
 
For 2., I tried playing Astro Bot the last stage, and I did not notice any inconsistency or audio lagging. I did not have the equipment to measure the latency, so I cannot give you the exact number. But do make sure the device is properly cooled (a nice heatsink and do not seal it in a box should be good), otherwise the CPU is throttled, and there will be sound breaking.
 
So as the long text in the description, the reason I ended up using Radxa Zero 3W is because:
 
It has at least two USB controllers. That is the requirement, because you need one for the USB gadget to connect to PS5, and another one for the USB host to connect to the USB speaker for output. The CPU is powerful enough. Before I used orange Pi One, but the single core performance is not fast enough, so I heard sound breaking. I guess maybe compare the single core score with rk3566 (the one on Radxa Zero 3W) might be a reference to see if a CPU is capable of handling the task. Higher single core score is better. With these 2 reasons, Radxa Zero 3W seems to be the bottom line you can find on market for such project. You can get a even more powerful board as you like.