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Confused Newbie with Questions about DAC's and Headphone Amps

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#1
Hi to everyone and glad to be here.

I'm new but have been lurking and reading lots of reviews for a while on my journey to enlightenment.

Okay, so I stream audio through my computer to either headphones, Drop SENNHEISER HD 6XX's, or to my stereo system, a 10 year old Yamaha receiver with about $2k worth of Klipsch speakers.

I've been on a bit of a buying spree lately having picked up a nice used Asus Xonar Essence STX sound card as well as a Topping E30 DAC. I fed both through to my Yamaha, the DAC via RCA jacks and the Asus card via optical out, and did back to back subjective sound quality tests using the headphones, and the E30 won.

I couldn't plug my headphones directly into the E30 because, well, I didn't have a RCA to 3.5 jack adapter and I've also read there may be some issue with driving 300 ohm impedance headphones with a DAC (low volume for example because of lack of amplification and possibly damaging something due to impedance issues.)

Well, I just received the adapter and low and behold there is a LOT of volume coming from the E30. More than enough to drive the heaphone's to crazy volume levels.

I'm confused. Am I going to damage the E30 or the headphones by using this combination w/o a headphone amp?

As part of my buying spree I also placed an order for a Schiit Magni Hersey amp today assuming I'm going to need it. This is a bit of a question mark of course: will the headphones sound better while being driven by this small amp vs. the Yamaha, or can I just plug into the E30? To my ears the headphones directly into the E30's are going to be hard to beat so that seems like the winner unless I'm going to damage something.

Needless to say I'm confused and could use some help deciding what to do. I'm tempted to stay with the E30 to headphones direct, and feed the stereo with the Asus card via optical for those less common occasions where I'm listening through the Yamaha.

Does this sound like a fair plan?

Thanks in advance for any suggestions.
 

boXem | audio

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#2
Hi to everyone and glad to be here.

I'm new but have been lurking and reading lots of reviews for a while on my journey to enlightenment.

Okay, so I stream audio through my computer to either headphones, Drop SENNHEISER HD 6XX's, or to my stereo system, a 10 year old Yamaha receiver with about $2k worth of Klipsch speakers.

I've been on a bit of a buying spree lately having picked up a nice used Asus Xonar Essence STX sound card as well as a Topping E30 DAC. I fed both through to my Yamaha, the DAC via RCA jacks and the Asus card via optical out, and did back to back subjective sound quality tests using the headphones, and the E30 won.

I couldn't plug my headphones directly into the E30 because, well, I didn't have a RCA to 3.5 jack adapter and I've also read there may be some issue with driving 300 ohm impedance headphones with a DAC (low volume for example because of lack of amplification and possibly damaging something due to impedance issues.)

Well, I just received the adapter and low and behold there is a LOT of volume coming from the E30. More than enough to drive the heaphone's to crazy volume levels.

I'm confused. Am I going to damage the E30 or the headphones by using this combination w/o a headphone amp?

As part of my buying spree I also placed an order for a Schiit Magni Hersey amp today assuming I'm going to need it. This is a bit of a question mark of course: will the headphones sound better while being driven by this small amp vs. the Yamaha, or can I just plug into the E30? To my ears the headphones directly into the E30's are going to be hard to beat so that seems like the winner unless I'm going to damage something.

Needless to say I'm confused and could use some help deciding what to do. I'm tempted to stay with the E30 to headphones direct, and feed the stereo with the Asus card via optical for those less common occasions where I'm listening through the Yamaha.

Does this sound like a fair plan?

Thanks in advance for any suggestions.
Yes, RCA to headphones works, but...
Output impedance of line output is usually about 100 ohms, not recommended to properly drive headphones.
Moreover, you are presenting a quite low load to the output buffer, it may distort a lot.
Summary, use a headphone amplifier if you want the things to do more than just work.
 

solderdude

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#3
've also read there may be some issue with driving 300 ohm impedance headphones with a DAC (low volume for example because of lack of amplification and possibly damaging something due to impedance issues.)
2V output for 300 Ohm means you can reach comfortably loud levels ony. When you don't need more then a 300 Ohm load won't be a problem.
Buffer opamps usually don't have any problems with it, no damage will occur and output resistances of a DAC up to 100 Ohm won't be very detrimental (some even prefer it)
So for the HD6XX it is no problem, still I would use an amp for this too as they can go well above 2V.

Using it this way with inefficient low impedance headphones isn't really recommended.
It is basically the same as wanting to use a Heresy, Magni or Atom to drive speakers directly.
Sure it will work but you MAY be overloading the output stage, maybe they used an opamp that can even drive low impedance headphones, maybe not. Maybe the output resistance is just a few Ohm, maybe not. We don't know unless it is measured or seen in schematics or in specs.
There are plenty of portable amps and even headphone outs on equipment itself that use a single opamp (that isn't really suited for the task) as a headphone driver.

So feel free to use the L30 the way you like it.. it is yours after all.
HD6XX isn't a problem but might not be optimal.
This is why there are separate headphone amplifiers in the first place. If they weren't needed they would not exist and headphones would have 2 RCA connectors on them.
 
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Thread Starter #4
Thanks for the reply's.

If I'm understanding correctly even though there isn't an overall volume issue now with the headphones plugged directly into the DAC there may be distortion due to not driving the headphones properly. Correct?

What about the question of sound quality from a large home theater AV receiver vs the tiny Heresy? Can one expect a tiny $100 headphone amp to sound better than a large AV receiver? The reviews I read here suggest the sound quality for even fairly high end AV receivers is just plain poor which is very surprising to me.
 

Jimbob54

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#5
Thanks for the reply's.

If I'm understanding correctly even though there isn't an overall volume issue now with the headphones plugged directly into the DAC there may be distortion due to not driving the headphones properly. Correct?

What about the question of sound quality from a large home theater AV receiver vs the tiny Heresy? Can one expect a tiny $100 headphone amp to sound better than a large AV receiver? The reviews I read here suggest the sound quality for even fairly high end AV receivers is just plain poor which is very surprising to me.
You mean the headphone out socket on an AVR? The headphone out on an AVR/ stereo speaker amp may have little or nothing to do with the signal to the speaker terminals (See @solderdude comment on how some headphone sockets are created) . The Heresy will likely be better than the majority of headphone outs on non dedicated speaker amps/ AVR. It only has one job , after all.
 

Nango

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#6
What about the question of sound quality from a large home theater AV receiver vs the tiny Heresy? Can one expect a tiny $100 headphone amp to sound better than a large AV receiver? The reviews I read here suggest the sound quality for even fairly high end AV receivers is just plain poor which is very surprising to me.
Sound experience is pure subjective. But yes, you can expect the 100$ item to measure better than a 1.000$ AVR.
 

Fluffy

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#7
The schiit heresy would undoubtedly be the best solution for headphones, and more versatile and future proof if you'll get different headphones at some point.

Actually, the dedicated DAC is the redundant part in your system. If your sound card has RCA and optical outs, you can plug the headphone amp straight to the RCA and the receiver to optical, and get rid of the dac. The importance of a dac is overrated and you already have one built into your soundcard and one in the receiver. Amplifiers are more important.
 

Dimitri

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#8
This is why there are separate headphone amplifiers in the first place. If they weren't needed they would not exist and headphones would have 2 RCA connectors on them.
Oh, C'mon....did you really open up the "If they weren't needed they would not exist" can of worms ? :)
The headphone amp "market" took off for a variety of reasons, not all technical. Pluse there is an almost unlimited supply of models out there , just as headphones , couple that with forum postings, youtube videos and built in "upgrad-itis" you got youself a "market". Needed or not.
 

Dimitri

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#9
I've also read there may be some issue with driving 300 ohm impedance headphones with a DAC (low volume for example because of lack of amplification and possibly damaging something due to impedance issues.)
Higher impedance headphones are an "easy load". The flip side is they might not be loud enough.
In your case "it sounds" :) like you are all set .
 
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Thread Starter #10
The schiit heresy would undoubtedly be the best solution for headphones, and more versatile and future proof if you'll get different headphones at some point.

Actually, the dedicated DAC is the redundant part in your system. If your sound card has RCA and optical outs, you can plug the headphone amp straight to the RCA and the receiver to optical, and get rid of the dac. The importance of a dac is overrated and you already have one built into your soundcard and one in the receiver. Amplifiers are more important.
As mentioned previously, I did back to back comparisons with both the DAC and sound card connected to the AVR and the DAC definitely sounded better. The nice thing about this test is that I could do it by just pressing/clicking on a couple toggles so there was no lag between different inputs. That test sold me on the value of the DAC, in my system anyway.
 

Fluffy

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#11
As mentioned previously, I did back to back comparisons with both the DAC and sound card connected to the AVR and the DAC definitely sounded better. The nice thing about this test is that I could do it by just pressing/clicking on a couple toggles so there was no lag between different inputs. That test sold me on the value of the DAC, in my system anyway.
Unless you level matched the two options down to 0.1 db and did that test blindly, your conclusions are not really valid. Sighted tests are notoriously deceptive and confirmation bias can cause you to believe pretty much whatever you want to believe. That's a difficult truth for most people to accept, because the natural state is to believe that our ears never lie to us. But they do all the time.

Your DAC could be more audibly accurate than the one inside your receiver, but unless it's properly tested, either via a proper double blind test or via measurements, you can't really know. And going down a path of blindly believing your ears in sighted tests can costs you lots of $$$ spent on expansive gear that "should" sound better – and subjectively does, because you were convinced it does by a raving review or a slick sales person.

The best advice for "newbies" is to let go with preconceived subjective perceptions, and stick with the science. That means rigorously proving that one device is better than another. And before that's possible, you need to prove that there is a difference at all. In a lot of cases (especially in DACs) that difference is mostly in your head.
 
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Thread Starter #12
Yeah, I get the subjective test part...but I stand by my comments in this thread.

So again, listening via headphones plugged into the AVR...

E30 DAC feeding the AVR via RCA cables.

For the Asus Xonar STX sound card I've hooked it up both using the RCA line-out ports to the AVR and I've used the SPDIF port feeding the AVR - both sound identical to my ears and noticeably inferior to the E30.

To compare sound quality it's a simple press a button and listen affair with literally 1 second separating the two.

My plan at this point is to try the E30 DAC with the Hersey amp when using headphones to see if I can hear a difference between that and with the headphones plugged direct into the E30. I'm expecting the amp to improve sound quality based on what you guys are saying but it'll be interesting to see if I can hear the difference.
 

solderdude

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#13
At low to normal listening levels you will probably hear no differences other than induced by level differences.
At impressive levels the difference should become obvious.
 
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Thread Starter #14
I may be convicting myself with my comments about subjective sound quality but can't help it.

Just did another test, this time with the headphones plugged directly into the Asus STX sound card and then switching back and forth with the headphones plugged direct into the DAC...and I can't tell any difference. This test is slower in terns of the switchover but I don't think that's skewing the results too much.

This test uses the ASUS headphone amp built into the card. And the DAC doesn't have much of any amplification. Anyway, I'll spare you guy any more of my subjective opinions since it's just going to draw ire.

The Heresy amp has shipped so it's going to be interesting to see if I can hear any difference with that installed. My son is anxiously waiting the result because he knows he's going to win by collecting whatever I'm not going to use. :cool:
 
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Thread Starter #15
Got the Heresy and hooked it up. Sounds great. Did more back to back tests against the Asus STX card and can't tell any difference. All good. I think my old AVR must be corrupting the signal because since bypassing that the sound quality is outstanding.
 

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