Tube Question - Do they need time to "Break In"

Just overnight or aprox 24 hrs.

No. They simply need to warm up to ideal operating temperature.

Tubes actually do not break-in,it is the opposite, they start ''breaking-down'', losing their efficiency hour-by-hour until they no longer provide musical satisfaction and have to be replaced.

Just keep it simple and enjoy them.....

>>02-07-09: Thorman
Just overnight or aprox 24 hrs.<<

Wrong.

Only the time taken to reach operating temperature; the dielectric is a vacuum.

Yikes, Audiofeil, play nice...

Follow-up question. How long do tubes take to reach operating temperature?

I ask because I'd imagine that wouldn't take more than a few minutes (not sure, which is why I asked), but my tube amp and pre sound better after an hour or so.

I know that's not break-in, but something is going on inside those vacuums!

Thanks everyone for the response...I'm changing tubes for the first time...