When you SSH into DietPi, you can install Shairplay from the software installer by issuing ‘dietpi-software’ in a terminal (choose ‘DietPi Optimized Software’).
Multiple Shairport devices:
If you are planning to use multiple Shairport devices on the same network, please make sure the hostname of each device is unique. This can be completed in dietpi-config > Security Options > Change Hostname.
Also, make sure you set unique names in the config file for shairport sync located: /etc/shairport-sync.conf.
Help, I have shairport on dietpi working on one Pi with a Hifiberry DAC, no issue. I cannot get it to work properly with my DAC (XCOM chip). There seems to be a bug with the sample rate, I get a weird fast, choppy sound. Is there a bug with the XCOM chip and shairport? I found some vague references but no solution.