ToneStack Pro
Tonestack Pro is a popular multi-effects AUv3 plugin. It offers extensive MIDI control, but Tonestack Pro as an AUv3 does not have a MIDI Input port. ToneStack Pro does not have a MIDI input port, it listens directly to external MIDI devices and apps.
Sending MIDI from Loopy Pro to the ToneStack plugin. To send MIDI messages from Loopy Pro to Tonestack Pro by targeting the MIDI at the Virtual MIDI Out port. Inside ToneStack, you can MIDI Learn MIDI sent from Loopy Pro to ToneStack Pro. You can use these MIDI messages to change presets, turn effects on and off and control effect dials and switches. Note that ToneStack Pro reserves some MIDI messages for special uses (such as CC 0). If MIDI learn does not work on a CC message sent from Loopy Pro, try changing the CC number.