Hi mattbatt77,
There’s a few ways to do this. If you want to keep both guitars plugged into the ES8, then you can use a stereo insert on the H90 to provide the output signal to 3&4. Place the stereo insert at the end of your H90 signal chain and set the Insert Mix parameter to 100%. On a program basis, you can bypass the insert for when you want to use outputs 1&2 and activate the insert to direct signal solely to outputs 3&4. In Perform mode, you could even assign one of the switches to control which output to send signal to by assigning it to the Insert bypass; you could even use an external aux switch for this.
The other way would require the acoustic guitar to always be connected to In 3 of the H90. By using Dual routing mode, each instrument would have a direct path to its amplification. On a program basis, you can switch around the Eventide presets to affect whichever instrument you prefer.
