Mac 6900 vs. Rowland Concerto Int. vs. MF KW 500

I am looking for an exceptional integrated and these are the three in the Seattle area I have come with. Have not heard the Mac and can demo the Kw. I have the Concerto this weekend. It sounds good but I do not know how to hook up my Rel subwoofer to it. So that is my first question. Secondly, Any thoughts on a head to head comparison of these three? Thanks.
I have not heard the Rowland Concerto but the Concentra II instead which I think is beautiful sounding though a little dry and in the same home, though with different speakers - B&W 802D instead of B&W N803, I heard the KW500 which to me is an amazing amp that was incredibly layered and nuanced and deserving of the high praise in the magazines.

hope this helps...
I have owned the Concentra I and the Mac 6900 and I strongly favor the Rowland. The review of it in the absolute sound (1999?) was spot on. It is magic. I disagree with the previous poster that it is dry sounding (if we're talking about the same piece, that is, not sure). Although I find it hard to qualify the phrase, it truly is 'magic'. Now, that having been said, I did trade it in on the 6900 to better drive my speakers (Tyler Linbrook System). Initially I had the Concentra driving the Tyler Linbrook monitors, which was incredible. When I bought the full Linbrook system, which allegedly drops down to below 3 Ohms in the bass regions, the concentra lacked the power. The Mac is great by the way, definitely worth the money - extremely revealing and full textured. Point is, it may depend on the speakers you have. Overall though, I like the Rowland better. Have not heard MF equipment.