Aune X1S Anniversary Edition DAC/Amp & X7S Amp Discussions | Drop

Jan 18, 2018

BubbleChamberOk thank you. That is correct, no distortion.

Jan 18, 2018

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Jan 19, 2018

MegazineThe problem with many receivers i’ve seen (even good reputation receivers like this one here) is that the headphone output impedance is very high, in most cases over 100 ohms, sometimes over 300 ohms. That happens because the unit does not have a dedicated op amp for the headphone output and they use the main amp with a very high resistor to amplify the signal to the headphone output in order to normalize the power output suitable for the headphones. For most headphones, that doesn’t respect the recommended 1/8x ratio rule (impedance Output of an amp should be no more than 1/8 the impedance of the headphone). What happens when the recommended rule is not respected is that the bass and mid / bass output is overly increased by a few db, and the sound is more muffled, with the bass response not as tight, not as clear, not well controlled, thus having an important negative impact on sound quality. This has nothing to do with power output capability of the receiver in headphone mode. For example my 2016 Onkyo audio/video network receiver has a headphone output impedance of 390 ohms. For my HD6xx, if we respect the rule, headphone output impedance should not be over 1/8 of the 300 ohms impedance of the headphone, in this case about 38 ohms (actually this is an average, because the impedance in the bass region of the HD6xx is higher than 300 ohms, closer maybe to 400 or 500 ohms, but that’s doesn’t change the conclusion here). That is why headphone amps exist and that is why most headphone amps have an output impedance of 10 ohms or less, and most good quality amps have an impedance output of under 1 ohm for compatibility with most headphones, including the very low impedance headphones which sometimes have an impedance of only 18 ohms.

Jan 19, 2018

Jan 20, 2018

PeteMtlWow thank you for this. I didn't know such a rule as the 1/8 existed. In my head, I was under the impression a high quality receiver would also work very well with headphones. Would you happen to know if my receiver plays well with this rule? I found this: 720 W Multi ch Simultaneous Drive (1 kHz, THD 1 % @ 8 ohms) http://www.pioneerelectronics.com/ephox/StaticFiles/PUSA/Files/Home/SC-65%20New%20Single%20Sheet.pdfI
I might have to Pioneer a call. P.S. I realized my receiver had volume locked at 0.0DB. It is now set to +20.00 max, and it goes very loud that I can no longer raise volume all the way up. Thank you!

Jan 20, 2018

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Jan 20, 2018

MegazineI checked the specs in your owners manual and nothing is said about the headphone output impedance of your receiver. If a dedicated headphone op amp was present, i’m pretty sure that it would be indicated somewhere in the manual or in the specs Sheet. My experience with most receivers like yours from Denon Onkyo Marantz Sony and Pioneer is that they have very high output impedance of their headphone outputs.

Jan 20, 2018

kokkat

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Jan 20, 2018

PeteMtlThank you for your post. If @Megazine had a high end Multimeter like the Fluke 289 (True-RMS Industrial Logging Multimeter), will he be able to measure the headphone output impedance of his SC-65 AVR? Or will that damage his main amp?
Is there any way of measuring the headphone output impedance safely and reliably?
Fluke 289 specs http://en-us.fluke.com/products/digital-multimeters/fluke-289-digital-multimeter.html#techspecs
Fluke 289 User Manual http://assets.fluke.com/manuals/287_289_umeng0200.pdf

Jan 20, 2018

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Jan 20, 2018

kokkatI think it would be far simpler and cheaper to buy an O2 amp and to plug it in the line out of his Pioneer Receiver. No need for a DAC, the Pioneer Receiver has one inside.

Jan 20, 2018

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Jan 20, 2018

PeteMtlInteresting and once again, thank you for the science. My AKG 7XX sounds amazing but I’m also a noob, coming from IEM’s like the Shure 535SE (love them). Now I’m curious if I‘m losing out on sound quality, since this is the reason I bought the AKG 7XX. I also ordered the HD6XX and I want to take advantage of them. This is an expensive hobby so I need to figure something out. Everyone, thank you for helping!

Jan 20, 2018

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kokkat

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Jan 20, 2018

PeteMtlYes, I totally agree with you, AVRs have the HP port just for late night adult movie watching :) I don’t think anyone ever uses it for listening to music. Why would I turn on an 11.2 channel AVR to listen to a 2 channel source using a 32 ohm headphone?
My post was mainly because I wanted to know if I can use my Fluke 289 for something like this without damaging the amp. :)

Jan 20, 2018

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Jan 20, 2018

MegazineSince you have two great headphones (I don’t own a k7xx but the general consensus is that it’s a good headphone, a bit brighter than the 6xx), it would be wise to buy yourself a DAC/Amp or just an amp if you plug it to your Pioneer Elite receiver. I am pretty sure that the DAC inside is good enough to be used as a source to your new headphone amp via the line out or zone 2 RCA ouput of your receiver. I do the same with my Onkyo stereo network receiver, I use an O2, and it works well In the living room. Otherwise you may choose a DAC/amp and plug it directly to your source, either a computer or a portable unit, again I do the same with a O2/SDAC combo plugged into my Macbook Pro in the basement/computer/home cinema room. Do what’s best for your own usage.

Jan 20, 2018

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Jan 20, 2018

PeteMtlWhat would be the correct method to connecting an O2 amp via “line out”? I‘m curious which type of method this would be, other then connecting directly through the headphone jack on my receiver.

Jan 20, 2018

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Jan 20, 2018

MegazineSimply a basic RCA to RCA stereo connector

Jan 20, 2018

Jan 20, 2018

PeteMtlIm currently streaming off my Apple TV 3rd generation. So I’m order to get this working I would connect my Apple TV using optical to O2 Amp and than O2 Amp to my receiver via RCA?

Jan 20, 2018

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Jan 20, 2018

MegazineO2 doesn’t have an optical in. And ATV doesn’t have an audio RCA analog out. So the way to do it is this way: On your ATV the outputs available are the HDMI and optical (? not sure here). Then plug the ATV via either the HDMI or Optical into your Pioneer Receiver and then via the line out or zone2 out RCA output of your Pioneer you plug it into your O2 with a RCA to RCA cable. This way it’s the Pioneer’s internal DAC than will decode the binary stream into music and via the RCA output your O2 will amplify the signal to your headphones. I do a similar setting except that my Onkyo receiver has an internal Airplay receiver circuit so I skip the ATV or Airport Express part and I stream directly from my Airplay equipped Onkyo receiver which then sends the analog signal via the line out/zone2 RCA output into the corresponding RCA input of the O2. No need for an external DAC this way.
If you have an Apple Airport Express, then you can use it as a DAC, it has a very good DAC inside from Wolfson/Cirrus Logic, and the Airport Express has an analog audio output. You then use a 3.5mm mini jack to RCA stereo cable which is then plugged into the minijack output of the Airport Express and then at the other end you plug the cable into the RCA input of your O2. You then can completely bypass your Pioneer if this is what you want.

Jan 20, 2018

Jan 20, 2018

MegazineIt would be nice to have your opinion on the HD6xx versus the K7xx In terms of audio quality, listening pleasure, just your own opinion as you feel it as an user.

Jan 20, 2018