Cambridge audio 851W

I'd be interested in any Cambridge Audio 851W owners feedback on a couple things.  First, I hear they run really hot.  Just how hot is really hot?  I have a custom, open front enclosure for my equipment.  No air can get into the back.  If I go this route I'm considering getting an AC infinity component fan.  Second, how does it sound?  The store I bought my 840C from can still get Cambridge Audio but doesn't have an 851W on hand for me to listen to or borrow to try at home.  I have a Mark Levinson No.28 preamp and a pair of Kef 105/3 speakers with the cube.  I was running them in a biamped configuration with a GFA 545 and a GFA 555.  Both amps are going south and I'm not sure if I'm going to fix them or not.  I'd sure appreciate any feedback.