Headphone Impedance For Denon AVR-S900W ?

[Sound Foundation]

Hello Everyone,

Holiday shopping is upon us and I would like to buy headphones to use with my Denon AVR-S900W audio video receiver.
In Sweetwater's listings I see that some headphones are available in several different impedences.
The Denon manual does not specify the headphone jack output impedence, and I have searched around on the web, and only found only cryptic answers that remind me of decades past trying to figure out the proper impedence tap to use on a dynamic mic head to connect to a transceiver.

Can anyone tell me either what the impedence of the headphone connection is for the Denon AVR-S900W or give me a general recommendation of higher ( 600 ohms ) vs lower ( 8 ohms ) impedence headphones for audio video receivers in general ?

Thanks for any insight.

 

[DVDdoug]

I don't know but 8-Ohms is unusually low. 32-Ohms is more commonly the minimum. (For some reason, some IEMs are lower.) And, 600 Ohm headphones are also rare these days. (I THINK it's an old "standard" from the tube-days because tubes are 'naturally" higher impedance and higher voltage.)

You rarely see the actual output impedance published for a headphone amp/output. Normally, they just give a minimum headphone load. (It's the same with power amplifiers for driving speakers. They give the recommended speaker impedance, not the amplifier's output impedance.)

If the output impedance isn't low-enough (relative to the headphones) you get a voltage divider. That reduces the output voltage But a bigger issue is that headphone impedance isn't "flat" over the frequency range and the voltage-divider effect makes a bump in frequency response where headphone impedance is higher, and a dip where it's lower. 600-Ohm headphones are high-enough that the frequency will be "correct" or "as measured".

With lower impedance headphones (or speakers) you get more current, and therefore more power. (Impedance and resistance are "the resistance to current flow".) So typically, lower impedance headphones go louder (with the same voltage-output). But, you have to compare the sensitivity specs.

 

[staticV3]

Now I hope that someone more experienced than me can chime in, but I believe that page 141 of the service manual shows a pair of 447Ω resistors in parallel with the headphone jack:

 

[staticV3]

If you want good sound with headphones, then you could always buy a headphone Amp like the Sabaj A10h, JDS Atom Amp+, SMSL SH-6, Topping L30 II, Schiit Magni+, Schiit Heretic, and plug that into the AVR's Pre Out for Zone 2.

That way, you can have perfect output impedance and as much volume as you need.