Thorium has a special client station called a sound player. This is a station specifically dedicated to playing sound effects with macros. The main purpose of this is to replicate the functionality of existing sound effects players, like Quartz Audio.
Using this sound player station is easy. Just configure it like you would any station in the client config or sets manager. Then, any 'Play Sound' macro configured to play through the sound player (which is default) will play through the sound output of that client.
This works on computers running in the Chrome web browser or in the Thorium Client program. The 'Play Sound' macro also supports outputs with multiple channels, such as Motu devices over USB or Thunderbolt. That can be used to play specific sound effects over specific speakers.