Synergy Amps SYN-30 is the amp.
From the Manual
Continuous Controllers
The SYN30 also responds to MIDI continuous controller (CC) messages. These MIDI messages are typically used for “instant access” buttons on more advanced MIDI controllers – buttons that can be set up to directly select amp channels. When using CC messages, you don’t need to go through the programming process described above.
CC Number Function
56 Select Channel 1
58 Select Channel 2A
59 Select Channel 2B
64 Mute
( I call #58 Channel 2 and #59 Channel 3 )
When selecting a channel using CC messages, only a message with a CC value of 64 or higher will have any effect. Messages with a CC value of 63 or lower is ignored. The Mute CC (#64) will mute the amp if a value of 64 or higher is received, and will unmute the amp if a value of 63 or lower is received.
Thank You