[ohhgourami]

I recently purchased an amp with these specs:
 

2x 125W (AB, 20Hz...20Khz, 4 Ohm) {2x 130W DIN ?}

2x 180W (AB, 1Khz, 4 Ohm)

2x 190W (AB, 1Khz, 8 Ohm, DIN)

2x 302W (AB, 1Khz, 4 Ohm, DIN)

2x 30W (A, 20Hz...20Khz, 8 Ohm)

 
What I want to know is what would I need to do to connect my headphones (HE-6) to the speaker output section on this amp to make sure it only run in Class A and stay at around 30W (maybe less).  I understand that I need something like this: http://www.head-direct.com/Products/?act=detail&id=104
But would it ensure I would always run in Class A and would it lower the wattage too much?
 
If someone can add some more info on the technical side of how the amp determines how much power to output that would be great as I'm very curious.

 

[Steve Eddy]

 
It's not so much the amp that determines how much power to output as the load impedance.
 
The amplifier takes the input signal and amplifies it depending on how much voltage gain the amplifier has, i.e., Vin x gain = Vout. The load impedance determines how much current is to be drawn (I = E/R) and that determines the power (P = I x E). Basic Ohm's Law.
 
As for maintaining class A operation, if the amp can deliver 30 watts into 8 ohms in class A, then that basically means it can deliver 2.75 amps peak to the load before it switches over to class B. The HiFiMAN HE adapter uses 25 ohm resistors in series. If you were to run 2.75 amps through those, they'd have to be dissipating about 95 watts each (RMS).
 
Bottom line, your HE adapter would burn up before your amp switches over to class B.
 
In other words, you're fine.
 
se
 
 

 

[wuwhere]

I believe the HiFiMan adapter's 25ohm resistor has a low power rating. This offers protection as well to your 6. This resistor will burn first if you draw too much power from your amp.