I agree with Rodman99999 .
I have Mullard 5AR4/GZ34 Tubes [ Amperex - Holland are nice also and fall into the same Class ] that were well used when I bought them and have been in service for 7+ years in my System . They still Test as New and will probably outlast me .
If you can find NOS - NIB great , but you will pay big time for them . I suggest buying New Testing Used for $25-$35 . They DO have a better sound than the New Production Tubes that I have tried and have a much longer life-span .
I have Mullard 5AR4/GZ34 Tubes [ Amperex - Holland are nice also and fall into the same Class ] that were well used when I bought them and have been in service for 7+ years in my System . They still Test as New and will probably outlast me .
If you can find NOS - NIB great , but you will pay big time for them . I suggest buying New Testing Used for $25-$35 . They DO have a better sound than the New Production Tubes that I have tried and have a much longer life-span .