Running Benchmark AHB2 in bridged mode and 4 Ohm Speaker

George, there is no current sag.  More watts mean more current.  You are overestimating the importance of doubling into 4 ohms.  It's not important in this case.  What is important is how much power is available and how an amplifier handles various loads.  If you lowered the gain on the amp so that in bridged mode it would only put 240 watts into 8 ohms it would still put 480 watts into 4 ohms.  It would be doubling but would have the exact same current capability it does now.  The issue is just that when you double the voltage you also double the current so the power is multiplied by 4.  You just shouldn't think of the bridged total watts into 8 ohms the same as unbridged.  Think of it as doubling the power.  The bridged Benchmark will deliver 200 watts at 8 ohms and 400 at 4 ohms.  It will actually put out more than that at both 8 and 4 ohms but you still get twice the power at 8 and it doubles that to 4.  What's not to like?

To put it more simply for the nay sayers. 

If this "bridged" amp is ask to give 380w when the speaker is at 8ohm and can only give 480w when it dips to 4ohms it is clearly current sagging.

If that same amp "not bridged" can do 100w when the speaker is at 8ohms and can then give 190w when it dips to 4ohms it has almost no current sag.

I ask the nay sayers, which is going to remain flatter in frequency response driving those speakers????

Cheers George  

bridged will be as flat or flatter at every volume that unbridged is capable of.  Obviously.  Bridged can put out 100w into 8 ohms, 200 watts into 4 ohms and 400 watts into 2 ohms.  There will come some volume that is much louder than unbridged is capable of where bridged will start having problems keeping up.  That isn't relevant to most people, though.  Most people aren't running bridged because running stereo won't get loud enough.

George, Where did you find 480W/4ohm? Their website states 480W/6ohm.

Sorry your are correct it’s 6ohm as 4ohm they could not test, obviously current limited at 18amps and shut down, still not great 18amp shut down in bridged mode. And still 100w short of doubling into 6ohm anyway, still current sagging, should be around 570w not 470w

Benchmark specs given to Stereophile.:
" Output power, bridged-mono mode: 200W into 16 ohms (26dBW), 380W into 8 ohms (25.8dBW), 480W into 6 ohms (25dBW). Output current: 18 amps/channel, both channels driven, 18 amps shut-down threshold."

Cheers George