The Krell 400Xi will have plenty of power to drive the Ascent i. I had the Krell 300iL for a couple years and used it to power a pair of Ascents and then Odysseys. The sound was very detailed with good soundstaging and imaging. Very good tight bass. Because the Krell is very detailed and articulate it is very revealing of the source components and so is the Ascent I. Therefore, it's important to have quality sounding front-end piece becuase you are going to hear everything being played good and bad so it all needs to be good.
I liked the 300iL but my personal taste has since moved on to the sound that tube amps produce and the Krell SS sound is different from a tube sound. They are both good but I believe the difference is a matter of preference. You have to listen for yourself and then decide.
The 400Xi is an improvement over the 300iL. I listened to the 400Xi with Vantage speakers a few times along with a Krell SACD and I was impressed with the sound of the system enough to buy a pair of Summits. Overall, I think the 400Xi is one of the best SS integrated I've had the opportunity to listen to and a great value. The bass from the Krell is top-notch.
The Krell amp gets hot and needs to have plenty of ventilation but then many amps are heat radiators anyway.
