I use this setup.
Can't compare it to other amps though, as I haven't used any others with it. I do think they power them fine though, at least I can't hear any real flaws.
I do feel like the soundstage isn't all that impressive with the amp, but to some that might be a plus. I've heard some people complaining about the K601/K701's having too big of soundstage, but this is much more intimate.
Really, really love the mids on this setup though. The Little Dot I+ has slightly forward mids, and it pairs well to make a really fun, engaging sound with the K601's. Electric guitars really scream, and voices come through with great detail.