Is 10Ω output impedance too high for a headphone amplifier ?

[LegionOfHell]

I am looking to buy the Creative GC7 but the output impedance is 10Ω, Should I worry about this ? I want to pair the following headphones with it(through headphone out jack):

M-Audio Q40,
Monoprice Modern Retro,
KOSS Prodj200,
Creative Aurvana Live! SE,
Creative Aurvana Live! 2,
Sennheiser PX 100-II,
Panasonic RP-HTF600-S,
Pioneer Steez 808,
KOSS KSC75,
KOSS KSC35,
Jvc HAS160B,
Sony MDRZX110.

 

[staticV3]

10Ω output impedance will change the frequency response of low impedance dynamic driver headphones and IEMs.
It'll boost the response at the impedance resonance (~100Hz).

This can be advantageous when it fills in a hole in the headphone's stock response, or it can make the sound worse when there's already an emphasis in the stock response.

It also means that, depending on the headphone, you can no longer rely on measurements from Amir, oratory1990, Resolve, Crinacle etc for EQ purposes as those are made with a <1Ω headphone Amp.

 

[solderdude]

I am looking to buy the Creative GC7 but the output impedance is 10Ω, Should I worry about this ? I want to pair the following headphones with it(through headphone out jack):

M-Audio Q40, (absolutely fine, no change in sound)
Monoprice Modern Retro, (= Superlux) absolutely fine, no change in sound)
KOSS Prodj200, (absolutely fine, no change in sound)
Creative Aurvana Live! SE, (absolutely fine, no change in sound)
Creative Aurvana Live! 2, (absolutely fine, no change in sound)
Sennheiser PX 100-II, (absolutely fine, no change in sound)
Panasonic RP-HTF600-S, (absolutely fine, no change in sound)
Pioneer Steez 808, (unknown but is 16 ohm so not recommended)
KOSS KSC75, (absolutely fine, no change in sound)
KOSS KSC35, (absolutely fine, no change in sound)
Jvc HAS160B, (unknown, probably fine)
Sony MDRZX110. (absolutely fine, no change in sound)

10Ω could be an issue with some IEMs

 

[Vincent Kars]

As a rule of the thumb a damping ratio of 8 is recommended. Some think this a bit low.
So if you use headphones with a impedance of 80 or more, you are fine.

 

[roladyzator]

I have a GC7 and it sounds all right with any of my headphones: AKG K371, K702, Koss KSC75, Superlux HD-668B, Beyerdynamic MMX 100, Sony MDR-EX15 (which are 16 ohm IEMs, but they use a DD so they don't have highly variable impedance).

If you're interested in the SXFI virtual surround, I find it sounds the best (most convincing effect) with the Koss KSC75 for me.

 

[LegionOfHell]

M-Audio Q40, (absolutely fine, no change in sound)
Monoprice Modern Retro, (= Superlux) absolutely fine, no change in sound)
KOSS Prodj200, (absolutely fine, no change in sound)
Creative Aurvana Live! SE, (absolutely fine, no change in sound)
Creative Aurvana Live! 2, (absolutely fine, no change in sound)
Sennheiser PX 100-II, (absolutely fine, no change in sound)
Panasonic RP-HTF600-S, (absolutely fine, no change in sound)
Pioneer Steez 808, (unknown but is 16 ohm so not recommended)
KOSS KSC75, (absolutely fine, no change in sound)
KOSS KSC35, (absolutely fine, no change in sound)
Jvc HAS160B, (unknown, probably fine)
Sony MDRZX110. (absolutely fine, no change in sound)

10Ω could be an issue with some IEMs

How about these headphones:

AKG K702,
DT990 Pro 250 ohms
Sennheiser HD 58X Jubilee,
Sony MA900,
Hifiman HE-400,
Audio Technica AD900x,
Fostex T50RPMK3,
Philips Fidelio X2HR,
Grado SR225i.

Also, Do these headphones play well with other amps with 10Ω output impedance ? Like Sabaj PHA2 and Aune T1se ?

 

[roladyzator]

HE400SE (not sure if you meant that) could have issues since they're only 25 Ohm and 91 dB / mW.

K702 are OK (I have those).

Max voltage on GC7 is about 2.8V based on the specs, so a 250 Ohm headphone would be OK too.

32 ohms (Low Gain, 51 mW)
150 ohms (High Gain, 41 mW; Low Gain, 16 mW)
300 ohms (High Gain, 26 mW)

Too bad Amir didn't measure one and validate those claims.

 

[solderdude]

How about these headphones:

AKG K702,
DT990 Pro 250 ohms
Sennheiser HD 58X Jubilee,
Sony MA900,
Hifiman HE-400,
Audio Technica AD900x,
Fostex T50RPMK3,
Philips Fidelio X2HR,
Grado SR225i.

Also, Do these headphones play well with other amps with 10Ω output impedance ? Like Sabaj PHA2 and Aune T1se ?

10 ohm output R is not problematically high. Only for very few MA IEM's and some low impedance headphones.
High impedance headphones (above 64ohm) don't care about 10ohm output R.

Above 30ohm output R can become an issue with some specific headphones.

HE400 and T50RP are planars and have a flat impedance so they don't react to higher output R anyway.

X2HR may have 0.5dB more bass, the Grado too.

Headphone drivers don't rely on electrical damping as much as heavy woofer cones may do.

 

[DVDdoug]

It's not just the headphone impedance. The output-impedance and headphone-impedance makes a Voltage Divider. If the headphones were resistive (the same impedance/resistance at all frequencies) you'd just get a voltage loss and otherwise "sound quality" wouldn't be affected... If the output-impedance equals the headphone-impedance the voltage is cut in half (a 6dB drop in loudness). And you still may be able to get plenty of loudness.

But headphone impedance (or speaker impedance) isn't constant over the audio frequency range and that's what causes frequency response variations. So, it depends on the impedance and the headphone impedance curve and some have a flatter curve than others. (If the headphone impedance is high relative to the output impedance, the headphone will perform "as specified" or "as tested" and you don't have to be concerned with the impedance curve.)

In reality, you rarely get 6dB differences.