[Thomasr]

When it comes to driving "demanding" headphones (whether due to low sensitivity, high impedance, or both) I read a lot of opinions about how inadequate amplification will show up in the sound. How headphone X will "scale" with the right amplification, etc. etc.

In other words, subjective opinions.

Does an ordinary consumer audiophile have any means to test - objectively - their equipment to determine if the amp is being asked to operate beyond its capabilities?

As a real life example, I have the SMSL HO200 amp. It seems to have plenty of power, but I'm not even sure what the output impedance is - presumably its pretty low since this amp is broadly targeted and needs to be okay driving/damping consumer headphones with impedance as low as 16ohms.

Driving a set of 600ohm headphones requires voltage swing. Does the HO200 provide enough voltage swing? Beats me. The manufacturer specs don't say a thing about it. Is there a way to quantitatively measure or test for myself? Or is the closest thing to a "test" going to be plugging in a set of DT-880-600s and (while stroking my beard in a scientific way) saying "hmmm, yes, I believe I am hearing evidence of sufficient voltage swing?"

To be clear, I'm not asking the community to tell me whether the HO200 will drive the DT-880-600. I'm asking how I can objectively prove or disprove that amplifier X can drive headphone Y.

 

[Thomasr]

Bump.

 

[Shane D]

That is a tough call. My experience is this area is with the HE6se V2's. I tried several amps and the Liquid Platinum certainly had enough power. I think 4.2W @50 Ohms. Didn't do anything for me. Then I added the Schiit Loki which gave me even more gain and a nice chunk of bass. Sounded better and if I had stayed there, I might have been happy.

Turns out that I already had an iFi Pro iCAN and that with bass boost and 3D sound effects enabled, it was the one for me.
The Pro iCAN probably has about the same power at 50 Ohms, but it was more about the sound. And that is SO personal for each person.

My Violectric couldn't do anything with them (2.7W at 50 Ohms).

I think you can look for a range of power to get close, but you need to find the sound you like.

It must be a nightmare to match something like the Susvara. I am sure it would sound good on a Pro iCAN, but there are probably some high end amps that could truly make it sing. But you could spend a small fortune looking and testing.

 

[chesebert]

When it comes to driving "demanding" headphones (whether due to low sensitivity, high impedance, or both) I read a lot of opinions about how inadequate amplification will show up in the sound. How headphone X will "scale" with the right amplification, etc. etc.

In other words, subjective opinions.

Does an ordinary consumer audiophile have any means to test - objectively - their equipment to determine if the amp is being asked to operate beyond its capabilities?

As a real life example, I have the SMSL HO200 amp. It seems to have plenty of power, but I'm not even sure what the output impedance is - presumably its pretty low since this amp is broadly targeted and needs to be okay driving/damping consumer headphones with impedance as low as 16ohms.

Driving a set of 600ohm headphones requires voltage swing. Does the HO200 provide enough voltage swing? Beats me. The manufacturer specs don't say a thing about it. Is there a way to quantitatively measure or test for myself? Or is the closest thing to a "test" going to be plugging in a set of DT-880-600s and (while stroking my beard in a scientific way) saying "hmmm, yes, I believe I am hearing evidence of sufficient voltage swing?"

To be clear, I'm not asking the community to tell me whether the HO200 will drive the DT-880-600. I'm asking how I can objectively prove or disprove that amplifier X can drive headphone Y.

No. Ask the manufacturer to give power ratings for white noise at different load impedances. Pick the amp that doubles down to 16ohm rating.

 

[Thomasr]

No. Ask the manufacturer to give power ratings for white noise at different load impedances. Pick the amp that doubles down to 16ohm rating.

What do you mean exactly by "doubles down to 16ohm"? That the power output in watts follows a linear function with each doubling (or halving) of impedance?

 

[chesebert]

What do you mean exactly by "doubles down to 16ohm"? That the power output in watts follows a linear function with each doubling (or halving) of impedance?

Yes, unless the amp is current limited. Say the amp outputs 500mw at 120ohm, it should therefore output about 4w at the same gain into 16ohm. I mean at the end of the day, without a scope it would be hard to do your own objective work.

 

[megabigeye]

When it comes to driving "demanding" headphones (whether due to low sensitivity, high impedance, or both) I read a lot of opinions about how inadequate amplification will show up in the sound. How headphone X will "scale" with the right amplification, etc. etc.

In other words, subjective opinions.

Does an ordinary consumer audiophile have any means to test - objectively - their equipment to determine if the amp is being asked to operate beyond its capabilities?

As a real life example, I have the SMSL HO200 amp. It seems to have plenty of power, but I'm not even sure what the output impedance is - presumably its pretty low since this amp is broadly targeted and needs to be okay driving/damping consumer headphones with impedance as low as 16ohms.

Driving a set of 600ohm headphones requires voltage swing. Does the HO200 provide enough voltage swing? Beats me. The manufacturer specs don't say a thing about it. Is there a way to quantitatively measure or test for myself? Or is the closest thing to a "test" going to be plugging in a set of DT-880-600s and (while stroking my beard in a scientific way) saying "hmmm, yes, I believe I am hearing evidence of sufficient voltage swing?"

To be clear, I'm not asking the community to tell me whether the HO200 will drive the DT-880-600. I'm asking how I can objectively prove or disprove that amplifier X can drive headphone Y.

Maybe I'm not fully understanding your question, but you can figure out how much power any headphone needs for a given SPL with:
P_t = 10^t-e/10
P_t = power (in milliwatts) to reach volume "t"; t = target volume; e = headphone efficiency (in dB@1mW)
This is a way of saying that +10dB requires 10x more power.
The DT 880 is rated at 96dB@1mW, so to reach 100dB (for example) P₁₀₀ = 10^100-96/10 = ~2.5mW. P₁₁₀ = ~25mW, P₁₂₀ = ~250mW

You can figure out how much voltage/current is needed with Ohm's Law.
P = V*I and I = V/Z, so V = √(P*Z)
P = power (in watts), V = voltage, I = current, Z = impedance
So your 600Ω headphones would need V = √(0.0025W*600Ω) = ~1.23V to reach 100dB.

...And actually you'd need more voltage than that because your headphones' impedance goes over 720Ω at 100hZ. So more like V = √(0.0025W*720Ω) = 1.34V.

...And if you want some headroom, you'll probably want to calculate for 110dB at least, so √(0.025W*720Ω) = 4.25V

Your amp spits out 6W into a 16Ω load, and 4W into 32Ω, which is a steady 9.8V. Assuming that holds for higher impedances, that's 133mW and 117dB at 720Ω. You should be good.

It's past my bedtime and I hate how long it takes me to write this stuff out. I hope this was what you were looking for.

Oh yeah, and SMSL lists the output impedance of the HO200 as "near 0Ω", which I'd take to mean <1Ω.

 

[Thomasr]

Your amp spits out 6W into a 16Ω load, and 4W into 32Ω, which is a steady 9.8V. Assuming that holds for higher impedances, that's 133mW and 117dB at 720Ω. You should be good.

Thanks for the detailed reply. My only question is whether I can indeed assume a steady 9.8V at higher impedances.

 

[lantian]

Insufficient voltage swing will lead to clipping, which is the worst kind of distortion. Way to hear it would be raising the volume as high as you feel comfortable and listen for any cut of sounds,artifacts, distortion or modulation that does not occur when output is at lower volume. Basically if it distorts at high volumes there is not enough voltage for the headphones. This applies to only 600ohm phones, have not had any experience with lower impedance sets than 300(and those are very easy to drive usually).
Distortion at lower volumes will mean amp is nowhere near capable of driving the headphones. Load makes it a unstable or it just has nowhere near enough clean power to power the headphones.
Ps another way to hear if power may become an issue is rasing the volume on pot and listen if the headphones stop getting louder at which point your amp has ran out juice and has reached its limit.(do not really recommend doing this, quality amp would not reach such a point)

 

[megabigeye]

Thanks for the detailed reply. My only question is whether I can indeed assume a steady 9.8V at higher impedances.

I don’t have time to reply in depth right now, but if you look up the HO200 on goldensound.audio you can see the specs that he's measured. He doesn't specify power into 720 (or 600) ohms, but his measurements are all well above spec, with voltage going even higher into higher loads. I think power into the 300 ohm load translates to something like 14.5V!
Without seeing the actual measurements we can't know for certain, but I'm beginning to be convinced that your amp is capable of driving your headphones to deafening (literally!) levels, and then some.

Also, I think he found the output impedance to be 0.2ohms.

 

[Thomasr]

goldensound.audio

Bookmarked!

 

[Flak]

I've got lots of headphones, but for me it was a long journey of finding an amp that didn't clip or shut down on my test playlist while listening at my usual volume (higher end of what's considered "safe") with the HE6SEv2.

 

[Thomasr]

I've got lots of headphones, but for me it was a long journey of finding an amp that didn't clip or shut down on my test playlist while listening at my usual volume (higher end of what's considered "safe") with the HE6SEv2.

So what was that journey's destination?

I've certainly read plenty about how demanding the HE6SE is to drive, but usually framed in terms of bass rolloff or flat dynamics, etc. Actual clipping would mean the amp is way outside its specs.

 

[megabigeye]

If my mental math is correct, the HE-6SE require about 20x as much power as the DT 880 to reach the same volume. Yikes.