Within the first few hours analyzing amps with this APx515 I was able to identify tonal characteristics of the block end JTM45 and apply those specs to the replica amp.

This analyzer has the ability to take what I call a "DNA sample" of an amp and save it for future reference. Everything about the signal path, gain, frequency response, clipping, harmonics, distortion... It's mind boggling.

Definitely a game-changer. I have this unit on demo for a short time, so I'll be documenting as many vintage amps as possible and will be saving pennies until I can own one.