Final answer:
To configure the Tascam M-3500 for mixdown, use the BUS ASSIGN buttons to assign channels to the stereo mix and the GROUP ASSIGN buttons for submix groups. Refer to the user manual for detailed instructions.
Step-by-step explanation:
To configure the Tascam M-3500 for mixdown, you typically need to press the BUS ASSIGN buttons to assign individual channels to the stereo mix. Additionally, you might also use the GROUP ASSIGN buttons if you have submixed groups of channels. These controls allow you to route the signals from the various channels into the main stereo mix or groups, which you can then record or send to another device for mixdown. It's important to refer to the Tascam M-3500 user manual for detailed instructions, as the operation can vary depending on the specific setup and the goals of the mixdown session.