I was wondering that given the apparent stagnation of tube development, and given that tube based electronic designs have been around for years, are the new tube based products just the same old designs with new face lifts? What can possibly be new about the new tube products (unless they're hybrids) given that most prized tubes are 40 years old, the tubes have been around for a long, long time and thus are a very mature technology? I can understand solid state equipment getting better because there are constantly new developments and breakthroughs in chip and IC technologies. This doesn't seem to be the case with tubes. So, my question is whether the manufacturers are rehashing the same old and if we may be better off getting 40 year old products on the used market for a small fraction of the price of the new tube designs?

If you're going to explain technical aspects of design, please explains in layman terms. I'm not an engineer.

Thanks