[Chris J]

Quote:

If I understand correctly how amps improve SQ, there are two ways: 1) increase the impedance of the system similar to adding a 75ohm adapter to ER4P; 2) to reduce clipping during peaks.
 
I am sure an amp can improve SQ a bit due to 1) but 2) shouldn't play much a role for light Jazz.
 
Am I right???
 

+4 on the low amplifier output impedance, the lower the amp output impedance the better.  This is not digital transmission line where "impedance matching" is important or desired.
 
A very good amplifier just SOUNDS better.
 
For example...........................
My AKG Q701 'phones sound awful direct from my notebook computer or iPod and sound merely OK direct from my iPad.
You don't have to spend massive bucks............I like the sound I get out of my iBasso D12 DAC/Amp combo.
 

 

[Head Injury]

Quote:

An amp will increase the input impedance that is seen by the source, which will improve the performance of the source. It will also decrease the output impedance that is seen by the headphones, which will improve the response of the headphones. The general rule of thumb is that you want very high input impedance and very low output impedance in all components in your signal chain, in relation to what they're hooked up to.

Correct me if I'm wrong, but isn't input impedance fairly standard across amps? And not all amps will decrease output impedance, many have high output impedances at all prices. The key is to find one that does have a low output impedance, not always an easy task when the spec isn't published.

 

[Chris J]

Quote:

Correct me if I'm wrong, but isn't input impedance fairly standard across amps? And not all amps will decrease output impedance, many have high output impedances at all prices. The key is to find one that does have a low output impedance, not always an easy task when the spec isn't published.

yeah...............just about any headphone amp should have a high enough input impedance to keep you out of trouble
 
as for output impedance, I agree, manufacturers are awful when it comes to publishing the output impedance.
 
you could try asking them..............I asked Schiit for output impedance of Asgard:    0.5 ohms..........excellent
output impedance of Valhalla:  20 ohms.........a bit high isn't it?   But some folks like it with K701s.........what can I say?
 
 
 
 

 

[Iniamyen]

Quote:

Correct me if I'm wrong, but isn't input impedance fairly standard across amps? And not all amps will decrease output impedance, many have high output impedances at all prices. The key is to find one that does have a low output impedance, not always an easy task when the spec isn't published.

Not necessarily. It's dictated by the input stage of the amp, as well as any passive volume controls that are placed on the input stage. It can vary significantly between amps.
 
You are correct that not all amps will "decrease output impedance." I was saying that in the context of why you would get an amp so I was listing this as a potential benefit.
 

 

[Chris J]

I think you mean to say not all headphone amps have a low output impedance.

 

[Iniamyen]

I meant it the way I said it. If you have a source with some output impedance, then adding an amp between your source and your headphones may or may not decrease the output impedance, when you're looking at the system of the headphones + whatever is driving them. This distinction is important because "low" has to be quantified, and what's low with a pair of 300Ohm Sennheisers may not be low when driving 32Ohm IEMs.

 

[Chris J]

Quote:

I meant it the way I said it. If you have a source with some output impedance, then adding an amp between your source and your headphones may or may not decrease the output impedance, when you're looking at the system of the headphones + whatever is driving them. This distinction is important because "low" has to be quantified, and what's low with a pair of 300Ohm Sennheisers may not be low when driving 32Ohm IEMs.

Then it is just sematics and we are driving at the same thing.
 
An amp will not lower output impedance.
Assuming we are talking about voltage amplifiers, i.e the input is voltage, the amp has a voltage gain, and the output is voltage, the amp may be considered a voltage source:
 
An amp will have an output impedance which may be lower or higher, depending on the design of the amp.
I would argue that for a solid state headphone amp that anything below 5 ohms is low enough for alomost any headphone.
And if you are going to use a solid state headphone amp, why would you want one with a high output impedance?
Transistors are inherently low output impedance devices so may as well use that characteristic to your advantage?
 
Sticking to the original topic, why use an amp for listening to light jazz?
Answer:
more output voltage,
more output current
more power
basically More Headroom.
 
I think the OP has lost interest!

 

 

[garynarcissus]

 
The necessity of amp is related to the demands of the headphones. For a high impedance headphone, amp is necessary and it will greatly improve the quality of the sound against the output directly from the source.
 
 

 

[stv014]

Quote:

The necessity of amp is related to the demands of the headphones. For a high impedance headphone, amp is necessary and it will greatly improve the quality of the sound against the output directly from the source.

 
Well, it is not so simple, impedance is only one of the factors that determine the "demands" of a headphone. Higher impedance is also only more difficult to drive in one aspect: more voltage required for the same power. In a number of other ways, it is actually easier. Obviously, when the source cannot output the necessary voltage for the desired loudness with low enough distortion, that is a problem. However, often the perceived great quality improvement is simply the result of badly done subjective testing (not matching levels, bias due to knowing which source is which, etc.).
 

 

[Chris J]

Quote:

 
Well, it is not so simple, impedance is only one of the factors that determine the "demands" of a headphone. Higher impedance is also only more difficult to drive in one aspect: more voltage required for the same power. In a number of other ways, it is actually easier. Obviously, when the source cannot output the necessary voltage for the desired loudness with low enough distortion, that is a problem. However, often the perceived great quality improvement is simply the result of badly done subjective testing (not matching levels, bias due to knowing which source is which, etc.).
 

A good example of this "perceived great quality improvement":
I tried comparing my $300.00 iBasso D12 Amp/DAC to my $300.00 Matrix M Stage.
The Matrix should sound way better because it is a dedicated amp (I was using the DAC in the iBasso, I was only comparing iBasso amp section to Matrix amp).
But it only sounds slightly better than the iBasso.
 
OTOH,   I think the iBasso D12 sounds a lot better than the DAC and headphone amp in my Notebook computer when I plug iBasso into the USB port on the Notebook.
So you could say the law of diminishing returns starts to apply here!
 
I agree with your statement that in some ways High Impedance phones are easier to drive, an Op Amp would rather drive a high impedance than a low impedance, assuming the Op Amp has enough power supply voltage to support it.

 
 

 

[fatcat28037]

 
According to this chary the eardrum breaks instantly at 160db

 

[TMRaven]

Oh how I love that 150db chest wall begins to vibrate sensation.  The joy of hearing loss.