Hello, just posting to clarify what ASIO Guard (roughly) is.
ASIO Guard is a two-levels buffer technology. Although with different names, most DAWs employ a similar facility (Logic, Studio One and Reaper for sure do).
This means the application works with two buffers: 1. the device buffer (set in the device control panel), and 2. a pre-processing / pre-fetch buffer, larger than the device buffer, used to increase performance and track count.
Indeed, ASIO Guard cannot be used on signals you are playing/recording, as this would mean playing with an unusable latency.
An example.
Let’s say we have a device buffer of 32 samples, totalling less than 8 ms and ASIO Guard set to maximum, thus being over 100 ms. All tracks that don’t rely on near-zero latency are processed on the ASIO Guard path with a larger buffer in order to have a smaller performance impact - this is not possible for tracks being record-armed/monitored/played live: these tracks must be processed with device-buffer latency, otherwise in this example one would play with a latency exceeding 115 ms.
In a nutshell, without ASIO Guard, all tracks / instrument would be processed with device latency, much reducing the total amount of tracks - any track which is being played live, cannot use AG and must be processed with device latency in order to be playable.