I have gone over most of the pro products and my absolute favorite are the Yamahas when all you need is 4 Ohm stability is okay. They produce no fan noise in use and they are very reliable - Yamaha is very high QCed - and performance is transparent with excellent SNR. In addition, the rack mount ears come off if you don't like them in your set up.
After trying several other brands, and considering far more.... I ended up with Yamahas in my main 2 channel active system. I could not ask for better amplifiers. I like these better than my former McIntosh amplifiers. These Yamahas have more power and I would wager higher performance - and all at a lower price. I don't care that much about 'pretty' looking hardware at this point; function is the most important factor to me. If I was obscenely wealthy, sure, I would load up the rack with very pretty exotic amplifiers.

I would go with Halcros..... some of the best measuring/performing amplifiers in the world(but not audibly better - they simply have the best measured performance you can get).
Here is a peek at the Yamahas in my main system:
http://www.linaeum.com/images/wmaxcomponents_1.jpg
-Chris