That's dependent on how high they are biased into Class A. Mono blocks are in my future, but I'd want them biased pretty highly into Class A. As a result they would get pretty warm.
It is interesting that he would place the caps next to the heat sink but of all my readings on the Kismet amp before I decided to purchase some myself I never came across people having issues with caps going bad and He's been making Kismets in Khartago cases for a while now I believe. And like others have said Klaus has a pretty good warranty.
When I measured my voltage out of my outlet I got anywhere from 121 to 124 which Klaus said is on the high side compared to others and if I remember right he set mine at around 122.7. With my SS8's I have to crank the volume pretty high for about an hour before the Kismets start getting hot and even then I can touch the top without issue. Now my Kismets have double the caps and ps as compared to what AGS has here so don't know if that's apples to apples or not. The Job 225 I tried with them got so hot I probably could have fried an egg on top. And I live in Phoenix by the way...
Withe the efficiency of your E3's I would imagine heat would not be an issue with something like these Khartago mono's that AGS has. My guess is the Kismets would sound great with your speakers with having the ability to give incredible detail while still being very musical.
I found this from the 6 moons review of the Kismets that Phil A posted a while back...
“The Kismets are class A for the first 10 watts or so and then the more power-efficient class AB thereafter. Class AB is a push-pull affair implemented here with Sanken 2SA1216 and 2SC2922 epitaxial planar power transistor pairs. These ring-emitter devices are noted for their long-term stability and reliability and crank out something like 17 amperes each or 34 amps per pair at 50MHz. They’re pretty much loafing in audio-frequency applications. Each Kismet has four such pairs, giving a peak current capacity of over 120A with 6 to 7 amperes steady-state. The inherently high bandwidth of these devices supports a frequency response of 2Hz to 500kHz, which according to Klaus allows lower feedback correction, reduces listening fatigue and distortion. It’s not by chance that these Sanken transistors are designed into several of the radically more expensive Burmester, Electrocompaniet and Symphonic Line amplifiers. “