I have had Heron and CJ preamps for many, many years. The Heron is one of the best. It would cost more to get a better sounding preamp. Larsman is right. Keith has retired. But my Heron amp and preamp are close to 15 years old and just fine. A CJ ET7S2 would be a close replacement. You may want to simply keep it and consider a different upgrade path.