I recommend the Harman Kardon.
There was a post with a bunch of bench tests and measurements ovver at audioholics for the Yamaha 2400 - it almost lived up to its wattage rating(very good in these times), but into 4 ohms the damping factor was around what you'd get on some tube amps, and the amp was being taxed horribly. the HKs do not do this, which suggests better amps - so don't worry about the wattage. Harman Kardon, NAD, Rotel, all give out conservative wattage ratings and have good high current amps.
I recommend you look at weight, over wattage. It tells a whole different story. If you find a 100x5 receiver that weighs 22 lbs, vs a 65x5 receiver that weighs 30 lbs, you're much better off with the 30 lbs receiver.
