I bought one used off eBay a few months ago and found that it sounds best with humbuckers through a very clean high headroom amp. I dialed in the Robben Ford tone with my Les Paul and Twin Reverb but its really sensitive. Just a hairs difference in settings makes a big change in tone. It also sounds great with my 67 Tele, especially on the bridge pickup. I read that if you take the 12aX7 tube out it's then basically a standard Zendrive and that's how I'm running it.