Best temperature for optimum tube performance

Why fan at the front and at the back where more heat would be injected out from the cabinet?
Output tubes and even signal ones produce considerable amount of heat stressing close by components like caps. If you cannot move equipment in open air then what you did is fine but it is difficult to tell if the cooling is uniform.
All tube spec sheets provide data at a specified ambient temperature. So if within that temperature they should work as intended.

G

Check it out: people taking this seriously. People who most of them never even notice a difference as their components warm up. People who will argue and deny there even IS any difference as a component warms up. But here they are imagining all kinds of crazy theories about how to optimize this imaginary tube temperature performance envelope.   

Sentence first, verdict afterward! Lewis Carroll knows you guys all too well. 

A snark, a snark! My Kingdom for a snark!

The tubes don’t mind the heat too much. The passive components like electrolytic capacitors would prefer it a little cooler. Although if you’ve been doing it for 40 years in that cabinet, with a fan, you’re probably fine. Just don't tell them that if you ever make a warranty claim.

It takes very little air flow to cool a chassis significantly. I've been doing it since the 70's. A couple of 12v 60mm PC cooler fans running on 3.5v are completely silent and cool the internal chassis from 50°C to 30°C on my tweeter PrimaLuna PL-5. Ditto a 100mm on midrange VTA M-125s.
PL-5: http://ielogical.com/assets/WinterBlues/PL5_Fans.jpg
M-125: http://ielogical.com/assets/M-125/BindingPost.jpg - note fan under tubes at front.

Thank you one and all for weighing in...
As an aside, I drilled a series of 1-1/4” holes in the upper back of the cabinet to provide convection venting....the two independent top drawers hide those holes.
I did install a small, quiet computer fan but it just couldn’t pull enough air to keep the gear from cooking.
(I was petrified to see millercarbon had replied.... I remain yet unskewered...love to witness the dust-ups he provokes.)
The temp gun is a great idea....