I got the split-case finished version from Aliexpress because I was too busy to make one, and it sounds good run-in, would sound better with Mundorf and silver caps and resoldered with Mundorf 9.5 silver content solder, however the cases are like ovens...all enclosed ....Im going to put at least a wire mesh on top....circular cut out with hole saw above each heat producing item at least.

You dont think that with better cooling/ventilation ie exposing the tubes outside of the case on top, and a vent above the transformer, might hypothetically increase the life span of heated components, say from 5-7 years to 12-14?? Just a feeling I get ... My chi-fi Mattise clone preamp popped the cap into a nice dome, reminisant of an Orthodox cathedral top .... after being on all the time and hot, in about 5-7 ? or so years ...

Are you finding that your case gets rather hot due to no ventilation? from the transformer and from the tubes? I cant help but feel that the life expectancy of the valves and transformer would be significantly reduced... I have a ready made one - split - but they both get hot ... I am thinking of raising the tubes via 3 holes to outside the case on top, while inverting the capacitors...and cutting a square hole above the transformer and putting aluminum mesh grounded - so that the hot air rises out of there...and greater convection cooling occurs... The only issue would be, would this lessen the faraday earth effect of the case and induce more hum...?