Tubes vary per unit.
Start by numbering or otherwise identifying each tube and 'roll' a pair at a time. For a small power amp w 2 different input and 2 power valves per channel there are 96 permutation. [2 x 2 x 24] With 2 same input tubes and 2 power tubes per channel, there are 576 permutations. [24 x 24]
Add in power line, humidity, temperature and CBLF vagaries...
IMO, rolling is an utter waste of time. One combination may favor one particular program to the detriment of another.
Start by numbering or otherwise identifying each tube and 'roll' a pair at a time. For a small power amp w 2 different input and 2 power valves per channel there are 96 permutation. [2 x 2 x 24] With 2 same input tubes and 2 power tubes per channel, there are 576 permutations. [24 x 24]
Add in power line, humidity, temperature and CBLF vagaries...
IMO, rolling is an utter waste of time. One combination may favor one particular program to the detriment of another.