I know Tekrø a bit, been to his studio a couple of times.
He is very picky about voltages to his Marshalls (2203,, 50 watts)
Runs them at the 240V setting and feeds them about 227 volts!
In the studio only one of the 12" in his 4x12 is working to avoid extra noise and phasingissues.
Live he uses 2 amps, delaying one a bit in stereo.
The 2 amps have serialnumbers after each other so they are as much the same as possible!
A lot of the sound on the old TNT albums has to do with producer Bjørn Nessjø.
You can recognize his sound by sitting in front of his amps while he is playing but that extra "studio sheen" is missing.
It also helps having incredibly high action on the guitar, Tekrø`s are crazy high, I have huge problems playing anything on them even if i don`t like my own action too low.
It makes the machinegun thing a lot easier though but not legatostuff