[SaLX]

"The approximate specs are input impedance 100K ohms, output impedance 120 ohms, gain about 15dB into a 300 ohm load like a Sennheiser HD600, max output about 10V into a 300 ohm load". http://www.bottlehead.com/store.php/products/crack-otl-headphone-amplifier-kit
 
So ideally we'd need a 800+ ohm headphone for this to work if we follow 'teh rules'? Clearly the Crack does the job, otherwise nobody would even consider them - there must be other factors at work here

 

[BillsonChang007]

"The approximate specs are input impedance 100K ohms, output impedance 120 ohms, gain about 15dB into a 300 ohm load like a Sennheiser HD600, max output about 10V into a 300 ohm load". http://www.bottlehead.com/store.php/products/crack-otl-headphone-amplifier-kit

So ideally we'd need a 800+ ohm headphone for this to work if we follow 'teh rules'? Clearly the Crack does the job, otherwise nobody would even consider them - there must be other factors at work here

Or maybe they are designed for Ortho driver?

 

[ssrock64]

  "The approximate specs are input impedance 100K ohms, output impedance 120 ohms, gain about 15dB into a 300 ohm load like a Sennheiser HD600, max output about 10V into a 300 ohm load". http://www.bottlehead.com/store.php/products/crack-otl-headphone-amplifier-kit
 
So ideally we'd need a 800+ ohm headphone for this to work if we follow 'teh rules'? Clearly the Crack does the job, otherwise nobody would even consider them - there must be other factors at work here

I have a preamp with 100 ohm output impedance, and it sounds fantastic with most of my cans. Sometimes the 1/8 rule doesn't really hold up well to subjective perception.

 

[LugBug1]

  I have a preamp with 100 ohm output impedance, and it sounds fantastic with most of my cans. Sometimes the 1/8 rule doesn't really hold up well to subjective perception.

+1 
 
All my current amps are approx 120 ohm output and my 701's sound amazing out of them. The headphone doesn't have much of an impedance curve so they aren't affected. Signs that they are affected would be bloated bass and blurring. They sound controlled with tight bass (as tight as any other hp amp I've tried). I've always thought that the AKG flagships are very power hungry. I remember when I owned both the LCD2 and HE500 at the same time as the K702's and the K's always needed more volume on the hp amps that I owned at the time. (Audio gd, Xcanv3, Asgard)

 

[tomb]

JMHO, but the emphasis on output impedance of amps is a little much these days.  As you guys have discovered, not all headphones sound better with super-low output impedance.  Not all headphones sound worse on high output impedance, either.

 

[wink]

There's also the fact that one person's opinion is that it sounds good, whilst another listening to the same setup will say that it's rubbish
Yet, both people listening to the headphones properly driven would say that it was great.

 

[BillsonChang007]

I personally do not think the AKG K712/Annie is power hungry. They just need more power to sound better. I can drive it to my listening volume with just 50% of my iPhone's max volume..

 

[LugBug1]

 Think you missed the point Wink buddy...  Don't think there is an amp that will drive the HD600 objectively proper. 

 

[LugBug1]

^^ except this is the K712 thread (woops) 

 

 

[Mad Lust Envy]

I like the Annie's more intimate tonal characteristics, and if I could I'd buy them again over the K712, but ONLY if the pads were of the newer K712 variety. What I'm hearing of the K712 makes it seem less appealing to my personal preference over the Anniversary.

 

[BillsonChang007]

I like the Annie's more intimate tonal characteristics, and if I could I'd buy them again over the K712, but ONLY if the pads were of the newer K712 variety. What I'm hearing of the K712 makes it seem less appealing to my personal preference over the Anniversary.

I got the Annie based on your review xD enjoying it ever after but I would prefer slightly better instrumental separation from it though IMO

 

[Mad Lust Envy]

Then buy some standard k70x pads.

 

[BillsonChang007]

Then buy some standard k70x pads.

No thanks I am planning to get a blue cable for just to match the color.

 

[tomb]

  There's also the fact that one person's opinion is that it sounds good, whilst another listening to the same setup will say that it's rubbish
Yet, both people listening to the headphones properly driven would say that it was great.

What the heck does that mean?  The whole point is "properly driven."  That doesn't necessarily mean super-low output impedance in every case.  If that were so, neither OTL or transformer-coupled tube amps would ever enter the picture with audiophiles.  Yet they do ... and literally prosper.
 
Technically speaking, it's possible to over-damp.  Every oscillating system will have a critical damping factor.  By definition of a critical point, that means there are scenarios on both sides that are not at the critical point.  IOW, there are under-damped and over-damped scenarios.
 
The entire race for a high damping factor pre-supposes the assumption that every single headphone driver will react the same to ever-increasing damping factors.  It may work in a lot of cases, perhaps even the majority.  Yet, it's also a bit like saying every headphone ever made is the same.

 

[kman1211]

 
What the heck does that mean?  The whole point is "properly driven."  That doesn't necessarily mean super-low output impedance in every case.  If that were so, neither OTL or transformer-coupled tube amps would ever enter the picture with audiophiles.  Yet they do ... and literally prosper.
 
Technically speaking, it's possible to over-damp.  Every oscillating system will have a critical damping factor.  By definition of a critical point, that means there are scenarios on both sides that are not at the critical point.  IOW, there are under-damped and over-damped scenarios.
 
The entire race for a high damping factor pre-supposes the assumption that every single headphone driver will react the same to ever-increasing damping factors.  It may work in a lot of cases, perhaps even the majority.  Yet, it's also a bit like saying every headphone ever made is the same.

I personally never found the output impedance to matter near as much as people make it out to be. I found as long as the amp gives them satisfactory power and has good synergy with the phone then that's all that really matters with amplification.