The A/R II boards had 2 purposes. First to convert and output the DC voltages to the game board. Second to amplify the audio.
If you are using a switching power supply, I assume that you just want to use it to amplify the audio.
They can be used that way. I do that in my Food Fight cabinet. To amplify the audio, I just feed the 36vac from the Atari power block to the A/R II board. Then the output from that goes to the volume pot and speaker.
If I missed your question then disregard. This message will self-destruct in 5 seconds
