I've never tried them but did listen to a few demos. I clearly noticed a difference when they were compared to various 12ax7 tubes. Sounded pretty much like what they are: a solid state device. Why anyone would want to put these in a nice tube amp is beyond me. Why not just go and buy a transistor amp? O.K. so they are guaranteed for life and they claim no microphonics, big deal. I rarely have any problem with microphonics using regular tubes and I am willing to pay the cost of replacing my tubes periodically. Anyone who owns a decent tube amp probably isn't going to be worried about replacing preamp tubes when needed. It doesn't surprise me that Soldano is praising these things. After all, isn't he financially connected to Jet City?
