How long can preamp tubes last?


Good evening Ladies and Gents
Trying to learn! I have had a Shiit Freya + preamp for about 1 year now, and it has about 450 hours of play time, with original tubes.
Is it time to change the tubs? What tubes/brand would be recommended to purchase? 
As far as budget, I really have no idea what they cost.
Also, what does the expression" rolling the tubes" means?

Any information would be welcome.
Thank for reading.
rockanroller

Showing 1 response by bondmanp

Tubes in my Mcintosh C220 have been in place for almost ten years, used on average about 15-20 hours per week.  When I had the preamp serviced this past fall, I had the tubes tested.  They tested like new.  So, the answer is, a very long time.