Audio interface preferences are handled slightly differently in Max than most other audio programs, and you have levels of control that you need to understand.
You can turn audio on and off in this window (ezdac~ will update itself to show that audio is on).
The driver menu chooses your audio output interface. You can set your input device to something else. For example, you can use CoreAudio MOTU 828mk2 as your driver but use Soundflower 2ch as your input device.
I/O Vector Size is equivalent to buffer size in other audio applications. The I/O vector determines how many samples are sent to your interface at a time, and this setting determines overall latency. (I/O_Vector_Size/Sampling_Rate = latency delay in seconds) Smaller I/O vectors increase CPU load; larger vectors reduce load but increase latency.
Signal Vector Size determines how many samples MaxMSP calculates at a time (more on vector math later). Signal vector size can be equal to or smaller than the I/O vector size. When we start working with delay lines this setting will determine your minimum delay time (Signal_Vector_Size/SR = minimum delay time).
The DSP status window also shows your CPU Utilization. The value displayed (in %) only refers to how much CPU is being used by audio processing algorithms in MaxMSP. It doesn’t know anything about the load coming from the rest of your system and applications (use the Apple Activity Monitor for that), or even how much CPU is being used by Jitter (video) objects.