Hi there!
Thinking about driving my 250 Ω beyerdynamic Amiron Home headphones from a DAC2 Pro headphone jack. Anyone know what the headphone output impedance is?
I understand that at 2,1 Vrms maximum output the SPL and voltage swing will be limited, that's fine for now.
Cheers,
Roderick
Good question. I imagine 25Ω headphones should work well with this limited voltage swing. Are you able to drive your Amiron headphones to satisfying levels?
It's a good step up from output off of an iMac (2017) or Marantz NR1602 AVR. The iMac has only 1,4Vrms output I believe. Impedance is specced at < 24 Ω though so damping is alright. But detail is poor and the cans just don't come alive.
The Marantz supposedly has 400+ Ω output impedance. Damping is poor and the sound incoherent.
I can't read the markings on headphone amp IC on the DAC2 Pro so I can only say subjectively. Lower listening levels are satisfying with good transients and range. Certainly pleasant to listen to until I get that β22 headphone amp up and running :)
Genuinely interested in the impedance of this headphone circuit.
400Ohm sounds more like a line-level output (the DAC's line level output impedance is 500Ohm already). While it's possible they really do this, I wouldn't really call this an headphone amplifier.
However, we didn't measure the output impedance on the DAC2Pro. The headphone amplifier is designed to drive headphones down to 16Ohm and can output up to 0.1W. With your 250Ohm headphones, power output will be below this as about 16mW max. With 102db/1mW that should still give you plenty of power. The output impedance is definitely way lower than 250Ohm (a rough calculation gives me about 20Ohm, but that's just a calculation, no measurement).
Yeah, as someone noted about the Marantz NR1609, that headphone output jack does not attempt to hide that it's just a surround loudspeaker amplifier protecting a poor headphone out circuit.
Thanks for the quick calculation on the DAC2 Pro. It's pleasant to listen to even with this load.