Plugged in a friend's TL the other day to give it a test run and it carried a high freq oscillation (continuous ring) through every setting. I had it on my PP2+, but switched it to a 1-Spot, which only decreased the volume of it, but it was still there. It's in a true-bypass loop with a bypass-able buffer, so nothing before or after it in the chain to affect it, and it did it with and without a guitar lead plugged in. Any ideas? Or has anyone else experienced this?