Usually the best way is to start with the tubes the designer used to voice the device.,Unfortunately that isn‘t always practicable. In my experience the best way to start is by making sure what you got is performing at its best:
1. use Graphene Contact Enhancer from the Mad Scientist (madscientistaudio.com) on all pins.
2. use Duende Criatura or EAT tube dampers on all tubes. Not from personal experience but often acclaimed: Herbie‘s tube dampers seem to do a good job as well.
3. start by upgrading the small signal and rectifier tubes with the best NOS tubes you can find.
4. If NOS can‘t be found: in general (but not always): Japanese or German or Dutch tubes are better than Russian tubes which in turn are better than Chinese copies.
5. On output tubes there tend to be pretty decent reviews available on the internet.
Most of all: have fun and enjoy the music!
1. use Graphene Contact Enhancer from the Mad Scientist (madscientistaudio.com) on all pins.
2. use Duende Criatura or EAT tube dampers on all tubes. Not from personal experience but often acclaimed: Herbie‘s tube dampers seem to do a good job as well.
3. start by upgrading the small signal and rectifier tubes with the best NOS tubes you can find.
4. If NOS can‘t be found: in general (but not always): Japanese or German or Dutch tubes are better than Russian tubes which in turn are better than Chinese copies.
5. On output tubes there tend to be pretty decent reviews available on the internet.
Most of all: have fun and enjoy the music!