[JaZZ]

I've just tested the following two configurations:

E-MU 1212M (modified) line out → silver TRS/RCA cables → homemade RCA/TRS jack adapter cable → Silver Dragon → HD 600
E-MU 1212M (modified) line out → silver TRS/RCA cables → Corda Opera → Silver Dragon → HD 600

The E-MU 1212M doesn't have a headphone output, but its line outs can drive headphones properly. The noteworthy difference between the two configurations is the Opera headphone amp. I couldn't level the volume any other way than by ear, and blind testing wasn't possible.

There's definitely a difference: The direct path sounds drier, more direct, more energetic. The detour via Opera slightly smoothes transients, but makes the sound more refined and introduces a pleasant, unobtrusive liquidness. The perceived transparency is about the same. So despite the relatively clear difference I can't tell which sound I like better. I can only speculate that the Opera's active ground may have made it passably competitive despite the fundamental disadvantage of double amplification.

Another, earlier test offered a clearer result. The two configurations:

iAudio7 (headphone out) → K 701
iAudio7 (headphone out) → Corda Opera → K 701

There was no contest: The direct connection sounded better in almost every respect.

That's not to say that the iAudio7's built-in headphone amp is better than the Opera's. But the extension and complication of the original signal path in the second case could hardly improve the signal, make it more accurate.

That's something to be considered: If a sound card has the same output path for headphones and line-level devices, additional amplification can only offer any kind of sonic improvement if the soundcard's output isn't capable of driving headphones properly, e.g. due to high output impedance, undersized buffer capacitors or limited current supply. In any other case an additional amp will have to deal with the same output signal and add its own inaccuracies/colorations.
.

 

[odigg]

Jazz,

Thanks very much for doing a test. If the output impedance of both outputs are the same then doing a volume match is easier and I suspect they are not when using the 1212M line out and opera headphone out. Do you know the output impedance of the 1212M? Since it's a line out it might be quite a bit higher than 0. Could this explain the sound difference since the opera has probably has an output impedance closer to 0?

I might sound like I'm defending my original argument with a technical question. I'm not, just looking for more information.

Again, thanks for doing the test and posting your reply.

Quote:

Originally Posted by ILikeMusic /img/forum/go_quote.gif Such a test is designed to compare two identical items and it's not really applicable to a 'with an amp and without' sort of scenario.

As another poster made explicit, I'm not asking to compare an amp and no amp. Every sound card built into every computer has a DAC and an AMP. It's most certainly not something with current buffers and a potential 18V voltage swing, but every computer's sound analog stereo output has an amp.

Quote:

Also, in a consumer equipment environment an amp will almost always sound different in some way as there usually is no attempt to carefully match the interface between amp and source, and whatever mismatch exists can affect the sound, often even more than that provided by the additional gain alone.

I don't understand your comment above. What mismatch are you pointing at specifically? Interface between amp and source? The only interface I can think of is a cable.

I don't see why this would be specifically limited to a laboratory test. Blind/volume matched tests require some effort to set up but there are people do these tests at home with their friends.

 

[JaZZ]

Quote:

Originally Posted by odigg /img/forum/go_quote.gif Do you know the output impedance of the 1212M?

No -- also since it's modified (and not by me). But I can make a guess: According to the (perceived) difference in sensitivity between HD 600 (300 ohm) and K 701 (62 ohm) it may be around 200 ohm.
.

 

[spanimal]

I wonder if a cambridge 340 integrated would have a head out comparable to say a lehmann black cube ss amp. I heard one once and noted that the articulation and extension of the bass with 650 was like none of my existing equipment ie Yamaha receiver head out and MFxcan3. I need a reference ss and also a reference tube as the xcan is neither.

 

[royalcrown]

A lot of testing landed me at the conclusion that an amp is a very optional piece of equipment. In the case of pro amps, however, they offer non-SQ based advantages vs. a straight output:

-Some have monitor-out lines to make switching between headphones and speakers easy and convenient

-In the case of pro sound cards, it removes the need for a clunky (1/4 mono to 1/4 stereo involves a lot of bulky plugs) and awkward placement

-It brings the headphone jack closer and in front for easier switching

-It gives an analog volume knob which is pretty convenient compared to computer volume sliders

-In the case of pro amps, it gives 4 outputs each with their own volume control.

As far as pure sound quality goes, I can't say there's a sound increase other than giving headroom. While for most music I never clip the DAC output, I do clip on heavily dynamic classical music, which is about 20% of my music library. Informal testing along with some research has put me where, for my headphones (dt880) and very dynamic music, an external amp is necessary for more voltage swing. For the 100 dollars shipped I paid for my HP4, it was worth the money I paid, and the other features I listed above were all very important from a convenience standpoint for me as well.

 

[mbd2884]

Makes a difference, but not required for the AD900. I prefer to listen from my Amp, but when I'm on the road, I just listen from laptop and happy.

With the HD650, only from Amp. Which is why it is strictly a "home" headphone. It definitely makes a difference and required for the HD650.

 

[10068]

Quote:

Originally Posted by odigg /img/forum/go_quote.gif To be honest it really doesn't matter. Use the output of your laptop, your motherboard's onboard sound, HT Omega Striker, our whatever you have at home. If it's a relatively new product (made in the last year or two) that's better as the newer sound cards, even onboard sound on many motherboards and laptops, measure quite well and support 24bit/192khz.

lol! Sure. Believe me I am not a blind supporter of audiophile gear vs. mass market gear, but this statement is ignorant and just plain wrong. I do use and have used onboard sound at various times for various applications -- I even spent quite a few months listening to my Sony CD3000's on such a chip when I first joined HeadFi. But, even if they do support 24-bit and 88.2 -> 192kHz output, that doesn't mean (and you should probably assume they don't) have any of the following:

* Decent quality opamps
* Decent quality DAC circuits
* Decent quality ADC circuits
* Decent noise-reduction shielding and/or circuitry design (this is very important for a clean, quality output from a PC)
etc.


EDIT: The above becomes even more of an issue on laptops, as (IME) parts are typically of lower build quality, and even if they aren't, they're much closer together, which leads to a incredible increase in subjection to heat and most importantly RFI/EMI.

I am sure onboard audio has gotten a lot better since the last onboard chip I listened to using headphones (motherboard manuf. circa 2004) but there's no way it's ever going to be equal to dedicated sound cards. If it was, that would defeat the whole purpose of dedicated sound cards. It takes a decently intelligent person about 10 seconds to think of a handful of additional reasons that the subjective SQ (and specs such as THD, Signal-Noise ratio, etc.) of these onboard audio solutions does not need to be equal to dedicated PCI/PCI-E cards, and thus very likely never will be. Also, again wrt onboard audio solutions, you're talking about cramming audio gear right next to components that pump out tons of RFI/EMI, such as either of the Bridges, the CPU, etc. Plug in headphones on the average onboard sound chip 1/8" jack and move your mouse around. You will literally hear the mouse movement (not joking here). This never happens with a PC card that costs about 100$+, let alone the nicer ones.


That aside, I find this thread very informative and fascinating (thanks for posting it!), but I had to call you out on this statement.


Carry on

 

[odigg]

Thanks for your post. As you said, an intelligent person can come up with all sorts of reasons why one certain piece of equipment is better than an another. But reasons or being certain about something is not automatic proof that one piece of audio equipment is practically better than another.

That's the whole point of controlled listening tests. Just because something measures or is theoretically better than something else, that doesn't mean people can actually hear the difference.

And so I asked for controlled listening tests. Sure, onboard sound cards have electrical noise. But can you hear that noise when music is playing? Can you tell a difference between onboard sound and a DAC+amp combo in a controlled listening test?

 

[10068]

Quote:

Originally Posted by odigg /img/forum/go_quote.gif Sure, onboard sound cards have electrical noise. But can you hear that noise when music is playing?

High-frequency noise and distortion caused by EMI/RFI and-or crappy opamps gives me headaches and hurts my ears when listening for a while. Better soundcards don't.

 

[diditmyself]

It depends on the output opamp in your soundcard and if it's low or high impedance phones you're using. When using high impedance phones (300R), most opamps can drive them sufficiently without too much distortion (if the output voltage is enough). With low impedance phones (16R or 30R) you'll probably need a dedicated amp to drive them without distortion, unless the output opamp has a good current capability like AD8397 or LM6171.

There are some other reasons for using a dedicated amp: it's nice to have an analogue volume control, and if the phones are plugged to the soundcard the noise level will be the same regardless of the volume and is annoying when using efficient low impedance phones.

 

[logwed]

This thread is much more civil than I anticipated.

 

[10068]

Quote:

Originally Posted by diditmyself /img/forum/go_quote.gif There are some other reasons for using a dedicated amp: it's nice to have an analogue volume control, [snip]

This is going to sound stupid, but I wouldn't have thought of that. I couldn't agree more. Now, turning down/up the volume via a virtual pot knob in the audio software or a slider in Foobar isn't a huge deal, but it is easier and more 'natural' I think that if you want more or less volume, to be able to just reach a few inches and twist a pot. In terms of safety, this is MUCH preferable as even the quickest hand on a mouse probably will not be able to turn the volume down fast enough (in the even of accidental -0.0dB output which I know everyone has down at least once) -- unless you had the audio app open as your main program, in the foreground, hand your hand on the mouse already, and didn't have a screensaver on or anything like that.

Quote:

Originally Posted by diditmyself /img/forum/go_quote.gif and if the phones are plugged to the soundcard the noise level will be the same regardless of the volume and is annoying when using efficient low impedance phones.

Well, yes and no. A sufficiently designed and shielded souncard will not necessarily suffer from this issue. I can plug my Shures (see sig) directly into the analog output jack on my soundcard and I don't hear any hiss at all until about 75-100% volume, which is enough to make my eardrums puke.

Technically though, yes you are correct. Even better souncards have a noise floor (duh) and it's way easier for this to breach the gap between audible and inaudible if you're using phones that require very little power to be properly amplified. I am not going to argue with EE science or audio mechanics

That being said, I think that generally speaking the issue with noise floor is directly related to price -- a $50 sound card would likely easily have this issue, whereas a $100 probably would not, and a $200 most certainly would not. A card of $400 or more may not even have any audible noise at -0.0dB using sensitive IEMs. Granted this isn't a black-and-white truth but i've found it to be generally true thus far. This is ANALOG output by the way, I have very little experience with comparing digital output signal quality on varying price brackets of PC soundcards. It makes sense, though if you think about it -- higher cost means more financial and R&D headroom for the manufacturer, which means better parts, better manufacturing process and better electrical circuitry design. FWIW IMHO YMMV

 

[DoYouRight]

I would definitely be willing to meet up and experiment as I live in Morrisville and haven't met another headphile ever really, just my uncle who is a huge audiophile and has like 40 sets of speakers and amps/preamps.

I do often listen to my Grados and such out of my Ipod headphone out and am ok with it. Or even my laptop out. Though I am willing to think that more power helps to have lower volumes with more juice for details. But still willing to test.

This thread is actually great, because there is no troll ripping it up and it is really well thoughtout and calm from about 5 posts in.

 

[corrupt_file]

I currently have a HT Omega Striker sound card in my rig and I am considering for an upgrade, say, HT Omega Claro Plus+. I recently bought Denon AH-D2000 headphone, and since it's a low impedance(25ohms) headphone, I don't think I need to throw an amp at it... But when I receive the headphone I will for sure find out.
When I receive the headphone I will test it out with HT Omega Striker, and if I am unsatisfied with the result I might build myself a CMOY using AD8620BR op amp ($37 cad just for one chip... ouch) and see if I can spring it to life. If that doesn't work out, then I will make the final decision whether to go with Claro Plus+ (maybe Claro Halo instead?) or not.
When I do find out though, I will come back to this thread and share my experience.

On the side note: AD8620BR is the same op-amp used in Claro Plus+, which is considered to be one of the top end operational amplifier available for audio. And it costs an arm and/or a leg haha.

 

[odigg]

Quote:

Originally Posted by corrupt_file /img/forum/go_quote.gif When I do find out though, I will come back to this thread and share my experience.

Remember to try and match volumes when comparing amps or an amp to a sound card output. If the volumes are not matched then it's going to sound different simply because of the volume difference.