The heat is just a side issue. No relation to the overall sound. I borrowed another TX and the amp improved. Close to the same loading a-a, and tap points. On the 441 I found a few really silly behaviours, which would not have been there if the thing was properly coupled.The 431 is a fairly simple wind. Not nearly as complex as another I have used( and had wound, and seen the instructions for ). They're not bad, just not excellent.
If we want to build like Doc Bottlehead does, the Dynaco stuff is a reasonable starting point. Doc's stuff is adequate but usually leaves you wanting more, hence the upgrade steps he offers. It is also allowing him to put a product out at near the bottom of the price pile. Not criticizing Doc, just explaining as I see it. I hope it does not offend anybody.
regards,
Douglas