Originally Posted by Iron_Dreamer
You can get the adaptors at Guitar Center, among other places, they are about $10 each. To mod them, you just open them up and remove the wire connecting pins 1 and 3. The Lavry doesn't have a fixed output switch per se, you would just set the attenuator to the top level for the same effect. I'm sure it would have no problem working with an integrated amplifier.
I bought the adaptors at 8th St. Music in Philly for about $7 each. If I remember correctly, I moved the return wire from pin 1 to pin 3, removed the jumper between pin 1 and pin 3, and left pin 1 unconnected. I did whatever it says is preferred in the manual. It only takes a few minutes once the soldering iron is heated up. If you are hesitant to do it yourself I would be happy to do it for you.
Since there is no potentiometer, it wouldn't hurt to run the Lavry into a preamp. It does work effectively as a preamp unless you want to switch between multiple sources.