I used to own the KRELL Duo 175XD and the K-300i so I know how the new KRELL sounds. I loved it. I sold the 175XD with the plans of buying the KSA -i400 or a CODA #16. I got a deal on a used #16 so I went that way. However, I do miss that new KRELL sound.
I expected the i400 to be better than the 175XD and 300XD. That was confirmed to me by this dealer. However, what was surprising is that the dealer sells other amps that are in the same price range, and he was saying that the i400 is much better than the main line he sells. I think he said it kills the other amps he sells. He was trying to get me to buy some of the other gear in the past that he loved, but now his opinion is a bit different.
In terms of priority the i400 is the last item on my list that he thinks I should buy since I already have the CODA #16. He is not really trying to sugarcoat his opinion on the i400 to me.
The amazing part on the amp is the specs. It doubles down to 1 Ohm and can drive anything. It also does not get Class A hot and the sonics for me were the most relaxing amps I had owned (the 2 lower end XD ones). The only negative for me is the depth and 160lbs weight. A huge reason why I went with the smaller and lighter CODA #16. Though the C0DA #16 sounds so good in my office system. The plan was to use in in the Livingroom system.