I am currently using your "upgrade" KT-88 tube set in my RM-200 and am running it at your recommended bias settings per the owner's manual. I would like to try other tube types. I have set of your RAM branded Siemens EL-34 tubes that I would particularly like to try. The manual says that I can use these, but it does not recommend a bias setting for them. I assume that the setting for these would be less than for the KT-88s? What range would your recommend. Also, I recall that the RM-9 series could use many types of octal tubes. What types can I try in the RM-200 besides the KT-88, 6550, and EL-34??