Connecting headphone with low impedance to Nuwave DAC without a headphone amp.?


#1

I have a Nuwave DAC and a pair of active speaker for computer audio.

With the arrival of a new family member, I cannot use speaker at late night. So I am planning to get a decent headphone.

If not necessary, I don’t want to spend much on another addition of audio equipment.

So is it possible to connect a headphone with low impedance (like Beyerdynamic DT770 Pro, 32 ohm) directly to the DAC and still produce quality sound?

Thank you for any answer or suggestion.


#2

NuWave can easily drive 100Ω load but no lower.


#3
Paul McGowan said NuWave can easily drive 100Ω load but no lower.
Thank you for the answer.

But…do you mean no higher? It can drive headphone with impedance under 100Ω, right?


#4

No lower.

Higher impedance headphones and speakers are easier to drive. Low impedance slurps up power.


#5

No, I meant no lower. Any higher impedance is easy. You had mentioned 32Ω and that is lower - NuWave would struggle with that.


#6

ah…I guess I mixed up voltage and current in the consideration.

But still, I don’t quite get all.

Headphones with high impedance often benefit from an amp. This is what I usually read/hear.
So can I say that Nuwave alone could do a good job, given headphones with high impedance, and with an amp it will even be better?
Or it’s not?

Thanks so much for the tutoring.


#7

The need that high impedance headphones have for an amp comes from the fact that high impedance headphones require higher voltage drive to achieve high playback levels. High impedance headphones can be connected to the output of a medium power speaker amp without immediately being turned into smoke and ashes. They are also suitable for use with tube amps, particularly Output TransformerLess, which easily produce high output voltage but have limited current capacity.

Low impedance headphones will draw higher power from a lower drive voltage. This makes them suitable for use with battery powered portable equipment that has limited voltage available. The downside is that low impedance headphones require higher current drive at these lower voltages in order to have the power needed to produce adequate sound levels. This means that low impedance headphones also benefit from being driven from an amp, just that the optimal parameters of the amp’s output are different:

High impedance headphones need an amp with higher output voltage but do not need high current capacity.
Low impedance headphones need an amp with lower output voltage and high current capacity.

In all of our cases of power delivery the output impedance of the source should be significantly lower than the impedance of the load. With high impedance headphones this is easy, and the output impedance of most line level source equipment being typically 50~100 ohms is comfortably able to drive headphones with an impedance of 300 ohms or more. This output impedance not only controls the amount of power that it can deliver, but also the ability of the amp to ‘control’ the drivers. If the output impedance is not significantly lower than the headphone driver impedance then the sound is likely to be unclear and/or flabby.

Some (many?) headphone amps try to meet all requirements by providing high enough voltage output for high impedance headphones and high enough current to feed low impedance headphones. This is a compromise, and rarely works extremely well for all types.

If you are into a little math, the electrical equations are simple:

Voltage (V) = Current (I) times Resistance ®. Various forms of this are:
V=I*R, R=V/I, I=V/R

Power = Voltage times Current. Various useful permutations of this are:
P=VI, P=V²/R, P=I²R

Need more? cool

J.P.


#8

Thank you for the super helpful information which I am digesting with recall of my high school physics.

I think I have just one more question.
Nuwave DAC features a high current output stage.
So how about the voltage?
How can I know if it outputs the voltage required to drive headphones with high impedance?


#9

The balanced output should be about 4V which is enough to drive something like a Sennheiser HD-600 or similar to reasonable levels, but not “loud”. The downside is that while the design includes a ‘High current class A hybrid output stage’, the output impedance is something like 100 ohms - as I understand it, they put a resistor in series with the output to protect the output buffer from a shorted output. The 300 ohm impedance of many Sennheiser headphones is a reasonable load for this, but on the limits. The only real way to tell how they will work together is to get a set of headphones and a custom cable and try it out.

J.P.


#10
wingsounds13 said Some (many?) headphone amps try to meet all requirements by providing high enough voltage output for high impedance headphones and high enough current to feed low impedance headphones. This is a compromise, and rarely works extremely well for all types.
And which is why some headphone amps have multiple outputs, one for high impedance, one for low. Some also have dedicated balanced ouputs.

Great job, wingsounds!!


#11

Very informative JP.


#12

I may not have much to share these days, but I am happy to share and help where I can.

J.P.


#13

I have always considered your posts to be among the most helpful and enjoyable. I had noticed that we had not been hearing from you as much lately and am glad to see you back.


#14

A big ditto!


#15

Thanks. I continue to visit often but have had little to offer for the discussion these days. As I said, I am happy to share what I have to offer - hopefully this can increase some time in the not too distant future. This is still my favorite community of the several that I frequent.

J.P.


#16

Thank you for your patient replies and explanation.
I really appreciate it.

And now I have another question :smiley:
I’ve decided to get Senn HD600 and Schiit Asgard 2 which will be connected to Nuwave DAC with 2 RCA cables.
So my question is, while the XLR output of the DAC are already occupied by a pair of active speakers, can the DAC also output signals to the RCA end simultaneously and equally?

Will both the speakers and the headphones producing sound at the same time?
Is it okay to do so? Or actually not recommended (maybe the sound quality will drop)?

Thank you for another tutorial. :stuck_out_tongue:


#17

I have the very same DAC. I have the balanced outs connected to a Schiit Mjolnir and the SE RCAs connected to powered speakers (with a Schiit SYS passive volume attenuator in series). It works perfectly well with no sound quality degredation. I will say that I don’t need to use them concurrently though. The headphone amp is powered down when I’m using the speakers and vice versa.