[Ambientnoise]

Each output transistor needs to dissipate around 15 Watts, independent of signal level. You need really substantial heatsinking, just look at the ones Linley-Hood used as shown in the article. For a heatsink shared between two transistors, you need say 2 degrees C per watt or less.

Also, the amp is only 10 watts output so will not be “disco loud” especially with modern, relatively inefficient speakers.

I have used mine for many years, love them !