It's a shame that no one ever replied to this thread, since now this page shows up prominently when doing a web search for the NAD C270 or NAD C370.
So, to answer the original question for others who come along via web search in the future:
Yes, either of these two NAD amps should be able to handle 4 ohms while running in bridged mode. As I'm sure you know, (which is why you were asking the question), you do have to be cautious about lower impedances when running bridged (because that mode cuts in half the impedance that amp sees -- in other words, a 4 ohm load looks like 2 ohms to the amp).
But these two NAD amps in particular should handle the load with aplomb, because they have the built-in ability to compensate for the load presented. That's detailed in this Stereophile review of the matching C370, where they also show that the amp could drive a 1 ohm load when running in stereo, which means 2 ohms bridged is fine.http://www.stereophile.com/integrate...633/index.html