If your guitar uses a battery powered Preamp that does not have a dedicated on/off switch, it will be automatically powered on when you connect the 1/4" cable to your guitar output jack. (most Preamps now work this way)
If you have this, make sure to unplug your patch cable from your guitar output jack when you are done using your TWA!
If left connected, it will drain your Preamp battery.
Most acoustic/electric guitars have an on-board battery powered Preamp that allows you to control the guitar’s volume and EQ settings. Your Preamp battery may be located in a compartment near the strap button on your guitar (Taylor), or attached via a small Velcro bag inside of the guitar body. (several others)
After-market pickup systems that are considered “active,” will also have batteries.
It is important to also set the pickup signal INTO the ToneWoodAmp. Keeping all EQ levels flat and Preamp volume at 50% is recommended.