How do you compare 2 headphone amps?

Feb 17, 2014 at 5:10 PM Post #31 of 60
Also, if you want to compare amps using the same source, wouldn't you need a 2nd such device to split the LO signal into the amps you are comparing?

 
 
  Ugh... I was kind of hoping someone wasn't going to mention that, because I don't know why it works.  But the answer is no, you don't need to toggle-switch line-outs at the RCA level.  I have been using 1M2F "Y" adapters for decades and have never had a problem with ground loops/noises, or signal losses between multiple components.  This includes car audio installations that are a minefield of radiated EMI/RFI and ground loops galore.
 
I just got my adapter from radio hack, wasn't cheap but still $$ decently well spent. 

 
I have seen that some headphone amps have a Line input and a Line output , and I think this Line Output can be used to connect the second headphone amp, so no need of any Y adapter I think. But don't know if it's common on most amps? ...
 
Feb 17, 2014 at 5:47 PM Post #32 of 60
   
 
 
I have seen that some headphone amps have a Line input and a Line output , and I think this Line Output can be used to connect the second headphone amp, so no need of any Y adapter I think. But don't know if it's common on most amps? ...

Yeah many headphone amps also have preamp outputs to feed another amp, or a speaker power amp.  My darkvoice 337 and Millet hybrid do, and every once in a long while I feed the 337 line out into my Larocco PPA (solid state amp).  I don't normally do that though... it just seems wrong adding harmonic distortion to a relatively clean sounding solid state circuit (shrug).
 
Feb 18, 2014 at 4:58 AM Post #33 of 60
  Yeah many headphone amps also have preamp outputs to feed another amp, or a speaker power amp.  My darkvoice 337 and Millet hybrid do, and every once in a long while I feed the 337 line out into my Larocco PPA (solid state amp).  I don't normally do that though... it just seems wrong adding harmonic distortion to a relatively clean sounding solid state circuit (shrug).

 
I would have thought that those Line In and Line out on the back of some headphone amps were only the "same", just as a parallel connection, or am I missing something? (not sure if what I'm writing makes sense
redface.gif
... forgive my bad english...)
 
Feb 19, 2014 at 4:47 AM Post #35 of 60
Ah ok, so I will have to find some Y adapters just for the case that the amps that I will want to test in the future don't have a line out... but as I don't have any headphone amp at all at the moment, I think I don't need adapters for the moment, because for the first tests, this is how I'm planning to do it:
but first I have to explain how I'm currently listening music with headphones:
During the last weeks I'm using the HD600 from a friend (he bought a hd800 a few months ago) connected directly to the output jack of a an old sony cd player (ES) that I bought for cheap :) . It's pretty useful because it has a volume control and also a remote that controls the volume too. I find it great as is, but we always want to improve, don't we?
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BUT, before I spend my money and buy a headphone amp , I would like to be sure that I will notice a better sound quality (imaging, bass control...) if I buy a good headphone amplifier for the HD600.
With the psb2 switch box that I've ordered, I will first try a comparison test between the output jack of my cd player and my friends headphone amps ( I think he still has a beta22 and a spl auditor), so I will know if , FOR ME, I notice any improvement in sound quality when using a dedicated headphone amp, and if the difference is worth the cost of an amp. That will be very interesting for me I think. I'm planning to do it “blindly” : my friend will switch the toggle switch for me without telling me if I'm listening to the CD player or the headphone amp...
Can't wait to receive the switch box and make this comparison test...
 
Feb 19, 2014 at 11:25 AM Post #36 of 60
  With the psb2 switch box that I've ordered, I will first try a comparison test between the output jack of my cd player and my friends headphone amps ( I think he still has a beta22 and a spl auditor), so I will know if , FOR ME, I notice any improvement in sound quality when using a dedicated headphone amp, and if the difference is worth the cost of an amp. That will be very interesting for me I think. I'm planning to do it “blindly” : my friend will switch the toggle switch for me without telling me if I'm listening to the CD player or the headphone amp...

 
I'd recommend you go through the Philips Golden Ears training first - it taught me a lot about what to listen for. I'm looking forward to your results!
 
Feb 19, 2014 at 2:42 PM Post #38 of 60
  Ah ok, so I will have to find some Y adapters just for the case that the amps that I will want to test in the future don't have a line out... but as I don't have any headphone amp at all at the moment, I think I don't need adapters for the moment, because for the first tests, this is how I'm planning to do it:
but first I have to explain how I'm currently listening music with headphones:
During the last weeks I'm using the HD600 from a friend (he bought a hd800 a few months ago) connected directly to the output jack of a an old sony cd player (ES) that I bought for cheap :) . It's pretty useful because it has a volume control and also a remote that controls the volume too. I find it great as is, but we always want to improve, don't we?
biggrin.gif

BUT, before I spend my money and buy a headphone amp , I would like to be sure that I will notice a better sound quality (imaging, bass control...) if I buy a good headphone amplifier for the HD600.
With the psb2 switch box that I've ordered, I will first try a comparison test between the output jack of my cd player and my friends headphone amps ( I think he still has a beta22 and a spl auditor), so I will know if , FOR ME, I notice any improvement in sound quality when using a dedicated headphone amp, and if the difference is worth the cost of an amp. That will be very interesting for me I think. I'm planning to do it “blindly” : my friend will switch the toggle switch for me without telling me if I'm listening to the CD player or the headphone amp...
Can't wait to receive the switch box and make this comparison test...

Ha ha!!  thats about as polar opposite of a blind A/B as you can get, open source DIY amp+Head-Fi rig versus a PCDP.  Some PCDPs have surprisingly robust headphone outs.  its the internal DACs and implementations that (basically) stink.  They're loud, powerful inferior number crunchers if you will.  I used to be more into PCDPs and I still have a bunch.. I don't want to say too much more than that and taint your views any further though.
 
Looking forward to your listening impressions!!  Blind AB is always the best way to evaluate HF gear.
 
oh one more thing...  Its going to be cumbersome que-ing up CD tracks between system A and system B in your sessions.  You might want to bring duplicate CDs, so you're not having to load/unload CDs at every A/B switch over. 
 
Feb 20, 2014 at 2:50 AM Post #39 of 60
  oh one more thing...  Its going to be cumbersome que-ing up CD tracks between system A and system B in your sessions.  You might want to bring duplicate CDs, so you're not having to load/unload CDs at every A/B switch over. 

 
I'm not sure if I understand your last comment... sorry if my explanation was not well written...
I meant that I will use the CDP as the only source, and use the switch box to compare instantly :
- (“A”) the headphone output jack on the front panel of the CDP,
and
- (“B”) the output jack of a headphone amp that will be connected to the Line Out of the CDP...
… I think it should be an easy to do AB test, or am I missing something?
I also know that I will have to match the volume levels the best as I can (by ear), but I think it will be no problem because the cdp has it's own volume knob for the headphone jack output.
It seems that I can now post some pictures, so here is a pic of my cdp taken from internet:

And yes, the old Sony CDP is very good and very well build. I will also try it with my friends HD800.
biggrin.gif
 
 
Feb 20, 2014 at 3:47 PM Post #40 of 60
Oh right... got it now.  you're using the same CDP, comparing amped line out with its headphone out jack.  For some reason I was thinking you were using a portable CD player.  So disregard much of what I posted above.
 
Anyhow, looking forward to the results of your blind A/B sessions.  Your buddy sounds like a hard core HF-er... he'll know what to do.
 
Feb 21, 2014 at 6:21 AM Post #41 of 60
Yes exactly kramer5150, but thank you for all your comments, it makes me think and make some research and I'm always learning. (this forum is great and has so much information...)

I think I will receive the switch box during the beginning of next week and I will probably have to wait until the following weekend to be able to make some comparison tests with my buddy. He has had (that I know of) several different headphone and amplifiers, including the HD580, HD600, HD650 and now HD800. He sold me the HD580 (probably more than 10 years ago) and this still is my only own headphone and I love it. He had kept only the HD600 and HD800, and he has lent me the HD600 for some time so I can see if it's better than my HD580. But I'm not sure that I can hear any difference between the 2, and I will probably keep my HD580. (I've read that they are nearly the same headphones, with the same drivers).
Of all the amps he had, I think he only kept a beta22 and an auditor (or phonitor?).
Those are the amps that I will compare with the headphone out jack of my sony CDP.
The comparison tests that we'll make will also give me the possibility to listen to the differences between his HD800 and the HD600/580. It will be great and we'll need at least an afternoon to do this all .
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But I'll keep this thread updated as soon as I receive the switch box with the cables.
 
Feb 25, 2014 at 10:45 AM Post #42 of 60
I've received today the “PSB2-1” switch box that I've ordered a few days ago from this website http://mfspdesigns.files.wordpress.com/, and I also ordered the 2 cables which are high quality with two gold plated 1/4” plugs (sorry for my bad pictures):

 
It seems very well build and solid, all aluminum case with 4 small felt feet.
I've plugged it to my old sony speaker amp headphone jack and to my cdp headphone out jack, and...

 
... wow... I hear immediately that the output jack on my cdp is far better than the speaker amp's headphone out ! (I've matched the volume levels by ear). Switching from amp to cdp, I can hear WITHOUT ANY DOUBT that the cdp is far better in every aspect (FOR ME) , width of the soundstage, clearer sound, and the amp has more bass and the high frequencies are more reduced than the cdp. And I've also noticed that the speaker amp has a small left/right imbalance.
 
 
The switch box is really great, it's so easy to make sound comparisons... I can't wait to start A/B tests with headphone amplifiers, I'm sure it will not be too difficult for me to decide whether my HD580 can provide me an obvious better sound quality when it's driven with a headphone amp.
I will update as soon as I can do some A/B tests...
thanks for reading...
 
Feb 25, 2014 at 10:30 PM Post #43 of 60
I wonder how "healthy" the line outs are on your Sony? Electronics can fail / degrade over long periods of time. Is your channel imbalance something in the amp or the source RCA outs? Something for you to consider. Plug your buddys B22 into your Sony CDP and see if the same channel imbalance occurs. Even the slightest imbalance will throw off the imaging.

Very cool results....

Round two:
Beta22 -VS- Sony CDP jack

Have your buddy close his eyes and see if he can tell the two apart.
 
Feb 26, 2014 at 6:24 AM Post #45 of 60
I wonder how "healthy" the line outs are on your Sony? Electronics can fail / degrade over long periods of time. Is your channel imbalance something in the amp or the source RCA outs? Something for you to consider. Plug your buddys B22 into your Sony CDP and see if the same channel imbalance occurs. Even the slightest imbalance will throw off the imaging.

Very cool results....

Round two:
Beta22 -VS- Sony CDP jack

Have your buddy close his eyes and see if he can tell the two apart.

Yes the amp is old, and probably it doesn't sound as new but I own it since new (I think I bought it in 1997) and it still sounds excellent with my old Cabasse speakers from the same time. I didn't notice any obvious sound degradation over the years...
I will try my cdp with 2 headphone amps and if there is a channel imbalance in the RCA line out, I think it will be pretty obvious.
We will do the tests without knowing which one we are listening to, and we'll see what are the differences and which one we prefer. We will probably try to take some notes, so we are able to easily compare what we both think individually and see if we agree on some points... it will be interesting...
 

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