this wikipedia page dumble amplifiers are extremely influental to musicians amp builders manufacturers collectors etc their value is in their sound as said on the wiki page many amp manufacturers are building amps based on mr dumbles design the design is alive and available and influental the man himself is a living legend in many ways one could descripe dumble amps superior to many people they are just ask larry carlton or robben ford or carlos santana famous musicians if you dont know all the business either directly from the original amps or services from dumble or in some way related to his work similar products or any sale mentioning his name is worth a considerable ammount of money