I don't understand comparisons where one amp has a boost and the other doesn't. It may just be an SD1 but you are still hitting the front of the amp with alot more signal and it makes a big difference. Now maybe if you were just trying to see if you can get the marshall to sound like the Diezel then I can see it .
I have owned both and the Diezel can go places the marshall never dreamed of. I didn't watch the entire video so I don't know if you have the EQ's set the same. I'm pretty sure you don't. And I'm confident the depth isn't turned up on the diezel. If you really want the Diezel to come alive take those KT77's out and drop some EL34's in, it will make a world of difference.
Both amps sound good, not trying to hate on your thread. I just know from experience that these are 2 completely different amps