Originally Posted by Bassment
Not sure if you're agreeing or disagreeing with me, but RMS power is continuous, so the breaker trip time is irrelevant. It can burst way more than 1800W, like you said. But even at 100% amp efficiency (which it's not even close), it could only do 450W RMS per channel
Let me see if I can explain. The circuit and circuit breaker do not directly limit amplifier output. The amplifier will draw as much power from the wall as it wants until the breaker trips or until other factors like sagging line voltage effect the amplifier, or the amp overheats and triggers its thermal protection, etc...
The circuit has no way to stop the amplifier from drawing as much power as it wants other than by tripping the breaker. That's why we have breakers or fuses, to prevent devices from drawing high levels of current long enough to cause a fire.
Per notnyt's testing, the NU4 will continuously output 2x 1200W bridged at 60% efficiency. That means drawing about 4000W from the wall, which it will happily do, even on a 15A circuit.
So you can play a full-volume sine wave outputting 2400W and drawing 4000W on an NU4. And after doing so for about 20 seconds, the breaker trips.
20 seconds is a reasonably long time, certainly enough to be called continuous. I think notnyt uses a 10-12 second long sine wave as his criteria for continuous amplifier output.