Ozzy, That has never been my experience with any of Bob's tube amps (I've heard the 350 and Silver 700 monster as well.).
Context is very important. What was the preamp, source, and speakers used to evaluate the 350 that showed "severe" drop off of the higher frequencies? Were the tubes in the 350 stock? The stock Shuguang KT88 are on the bright side in my opinion compared to the for example the Golden Lion K88 reissues, which are more natural sounding but can sound a little recessed in the highs. Did the person who evaluated amp make sure the tubes were functioning normally?
Good thing about tube amps is that you can roll tubes and suit the sound to your taste to a certain degree.
Context is very important. What was the preamp, source, and speakers used to evaluate the 350 that showed "severe" drop off of the higher frequencies? Were the tubes in the 350 stock? The stock Shuguang KT88 are on the bright side in my opinion compared to the for example the Golden Lion K88 reissues, which are more natural sounding but can sound a little recessed in the highs. Did the person who evaluated amp make sure the tubes were functioning normally?
Good thing about tube amps is that you can roll tubes and suit the sound to your taste to a certain degree.