Get your tubes broken in first. I've seen recommendations of up to 300 hrs for burn in. Most average time is 200 hrs. Depends on the manufacturer of the tube.
I'm I tube nubie too. Just got my first tube integrated 3 weeks ago. Prior to that I was fortunate enough to demo an unit for 4 days with 3 sets of tubes. The tubes were KT88's - 6550's - and EL34's. They were all different sounding and could not pick a favorite. So I added the other 2 and have all 3 sets (all factory stock). Just crossed the 250 hr mark on my KT88's and will roll in the 6550's at 300 hrs. I think I have a good feel for the KT88's and like them but that's the only one I have listened to since getting it. So I have a reference point.
As far as warm up for me my unit has soft start and only takes about 5 min. When I do power off the unit and let the tubes get completely cold it takes about 10 - 15 min to sound good. Either way again for me after 2 hrs they don't get any better.
That's my experience so far.
I'm I tube nubie too. Just got my first tube integrated 3 weeks ago. Prior to that I was fortunate enough to demo an unit for 4 days with 3 sets of tubes. The tubes were KT88's - 6550's - and EL34's. They were all different sounding and could not pick a favorite. So I added the other 2 and have all 3 sets (all factory stock). Just crossed the 250 hr mark on my KT88's and will roll in the 6550's at 300 hrs. I think I have a good feel for the KT88's and like them but that's the only one I have listened to since getting it. So I have a reference point.
As far as warm up for me my unit has soft start and only takes about 5 min. When I do power off the unit and let the tubes get completely cold it takes about 10 - 15 min to sound good. Either way again for me after 2 hrs they don't get any better.
That's my experience so far.