Why do headphone amps have high output impedance?

[AstroBenny]

My understanding of amp output impedance is that you should aim to use headphones that have at least 8x the impedance than the output impedance of the amp.

I thought amps which had a high output impedance were just an example of cheap equipment but then..

I saw this..

 

http://www.vickershifi.com/products/paaurium/pathos-aurium-headphone-amplifier

 

A £900 headphone amp with adjustable output impedance of 16-1000 Ohm..

So..Why would you ever want to increase the output impedance and why is the minimum output impedance so high compared to much cheaper headphone amps?

[Enderman]

less impedance = more sensitive to EMI

[SSL]

26 minutes ago, Enderman said:

less impedance = more sensitive to EMI

 

This is literally wrong.

[Enderman]

6 minutes ago, SSL said:

 

This is literally wrong.

no its not

thats how electricity works

im not talking about amps btw, im talking about the speaker drivers impedance

[AstroBenny]

8 minutes ago, SSL said:

 

This is literally wrong.

So...

Can you explain?

[William5849]

It may have to deal with the ability for the headphones to work with different devices. You could plug them up to an iPhone and then crank the ohms up for a studio setup which can help give you more consistent sound. But the tonality of the headphones wouldn't change. So versatility, maybe.

[EndlessOyster]

27 minutes ago, Enderman said:

no its not

thats how electricity works

im not talking about amps btw, im talking about the speaker drivers impedance

But then you get speakers with a impedance as low as 2 ohms, oh they must be so shit with all the interference they get because of there low impedance.

[Pomfinator]

For now lets answer the basic question.

 

It has high output impedence b/c it's a tube amp. There, got your answer? Tube amps are meant for high impedence headphones or else they distort like crazy, most of them also put out less power at 32 or 50 ohms than they do at 300+ ohms.

[Enderman]

3 hours ago, EndlessOyster said:

But then you get speakers with a impedance as low as 2 ohms, oh they must be so shit with all the interference they get because of there low impedance.

no because speakers require way more power than headphones to drive because they are far less sensitive

i dont think your headphones need a 200W amplifier do they?

[SuicideAnomaly]

16 minutes ago, Enderman said:

no because speakers require way more power than headphones to drive because they are far less sensitive

i dont think your headphones need a 200W amplifier do they?

My RF-7ii's are sensitive little flowers...err, sensitive large flowers!

[MarcWolfe]

They're made for high impedence (OHMs) "audiophile" *cough* headphones which require more power to drive. They're not great for bass, continuous bass anyway. They have a quick punch to the bass but it can quickly taper off due to whats called "counter current". If you read up about different types of electric motors you may hear the term a bit.