I've read the bulk of this thread and I finally have a clear picture in my head of the different options.
My question is this: Why are the headpone outputs of integrated amps not already set up this way? If it is so cheap and sounds so good, what is it that makes manufacturers do something different?
I opened up my arcam alpha 10 to take a look at the headpone socket, and all I see are 4 resistors. Am I really doing anything different that what is already done inside the case by using the speakers taps?
The arcam alpha 10 is 100+ wpc in 8 ohms, can anyone guess as to how much attenuation I will need when driving a pair of audeze lcd-2? Would it be safe to hook them up without?
(Additional none related query below)
Something that has been bugging me is that when people talk about the power requirements of headpones, they talk about the amount of power required to make a certain headphone reach a certain db. Is this an average figure taken accross all frequencies, because I thought lower frequencies required more power?
When somebody says x amount of power will produce y db output on these headphones, then in theory, could that not be true for the lower frequencies?
The reason I ask here is I wonder if this could be the reason that driving headphones from powerful speaker amps produces favourable results.
Built-in amplifier headphone jacks are usually over attenuated and drop the power to the headphone jack too much. This may be due to liability issues with damaged headphones or hearing. The resistors in your arcam alpha probably over attenuate. You could replace the built-in resistors to get the amount of attenuation you want.
You can safely connect your headphones to the speaker taps but slowly raise the volume so you don't overpower the headphones. As long as you don't have noise floor (hiss) or volume control issues you don't need a resistor network with a solid state amp (tube amps tend to be more sensitive to speaker load).
For 100watts per channel I would recommend about 24db of attenuation.
Edited by robrob - 4/10/14 at 9:50am