But how do you "know" that a given heater setting is NOT frying your precious tubes over (maybe even) a short time?
Yes, good point.
To be clear, I'm not talking about running a tube that requires a low heater setting (101d, 45, 242, PX4, etc.) on a high heater setting (300b, T100, etc), for example. I'd never do something like that. The specific change here I'm referring to, is a minor one, in this case, moving from the 45 setting up one notch to the 242 setting on a Philips PT35.
Recall, some older model Lampi DAC's only had a toggle switch with two options: High heater or Low heater. So, back in the day, most tubes were not being run at the precise, optimal setting..
With our more recent Lampi's, we have options to fine tune. But yes, one has to consider the ramifications on tube life. I guess at some level, we are burning out our tubes every time we power them on. But, these Philips PT14 and PT35 are tough little buggers.
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)