Bridge or bi-amp? Which should I do?

NAD amps can be bridged, but when I did so with my 3400 and 2400 amps (sister products) to rum my Mission 765's, there was a very definite decline in the sound quality. The trade-off to maximizing power output(and there is always a trade-off) is the sound output took on a much harder edge. Bi-amping preserves all of the sonic/headroom benefits with absolutely none of the trade-offs.
In your case, I would have used one of the amps (the one with independent level control) for the HF and the other for the low; or the more powerful amp for the LF.

Pretty sure they do, as I tested them prior to this response.

I decided to bridge my amps and love the results. Big, open sound, huge soundstage.

I may be dense (may?) but, how are you intending to do this bi-amping? Do the high-level outputs on the C370 stay active when using the pre-outs? Or does it have main-ins, and you are going to use a Y-splitter off the pre-outs? And if either is true, does the amp have adjustable gain so you can match properly? Doesn't bridging or bi-amping with non-identical amops introduce all manner of potential to screw up something?

The issue of good sound is always a quest. For this reason, the audiophile is engaged in an activity not unlike that of a dog trying to bite its tail. Never ends.

My dear friend, why bother? Those components of yours will not take you far. Harshness, harmonic artifacts, lack of proper soundstage and sheer frustration will be sitting next to you in your listening room. Simplicity is of utmost importance regarding your issue. Integrated is simply not the way. Even in hoods this is a well known fact among the rappers. Why, then, do you even bother to complicate your life? Listen and learn, listen and be wise; now you won't be able to sell your gear even in the hood...

An old classic tube receiver, some loaded horn speakers and a good self powered sub will save you headaches. Will beat the crap out of what you have. Just post this thread in Audioasylum and wait for the fish to bite.

Listen and be wise...

There is a very good discussion of some of the benefits of bi-amping at www.sound.au.com if you are not alreaady familiar with it. (Rod Elliot's site.)

I recently sold my NAD 2400 and purchased the new NAD C270 amp. I have the integrated C370. Should I bi-amp my speakers or bridge the two amps?

I once talked to the folks at Bryston about bridging their amps verses upgrading to higher wattage. They said that when you bridge their amps while you get more raw power, you give up some of the quality of sound (i.e. soundstage, etc.). If that's true of a Bryston amp which is very 'bridging friendly', I wonder if it's not true of most all amps that a person would bridge. I am not an engineer but I followed their advice and went with the higher wattage amp instead of the bridging route. If I were you, I would bi-amp as well.

I would also biamp. I am not sure that NAD amplifiers like to be bridged. Happy listening

biamp, so as to not degrade your damping factor via bridging

Unless you are sure that the wattage, impedence, etc. is identical between the two, I'd suggest bi-amping (assuming your 602's are biwirable). Even if their spec's do match, I'd still be hesitant to bride them and run them as monoblocks. I'm guessing that the bridged integrated would not exhibit the same tonal qualities as the bridged solo amp. Just a guess though. A little experimenting would answer your question best. Happy listening.

...meaning different amps for each speaker?
If your speakers have 2 or more pairs of binding posts this is a perfect case to biamp your speakers.
On wonder to all other audiophiles I am not familiar with B&W line of speakers.