Review: JDS Labs O2 (Black edition) + O2/ODAC discussion

[xnor]

  Ok, I'm gonna try to explain it as I understand it, anybody correct me if I'm wrong...

Okay, less of a correction but more like a few additions and adjustments.
 

DAC: Digital-Analog Converter. Is the responsible of transforming your digital signal to analog signal and this way allowing you to listen to it through your headphones. The quality of the transformation may be good or bad, depending on the implementation of the DAC itself. Each DAC has its own technical characteristics and resolutions. The DAC is gonna be the first bottleneck between your files and the final sound, therefore if you have a very high quality file but your DAC is not capable enough, you will never get the quality of the original file on your headphones.

Most better DACs support 24 bit samples and reach about 20 bits of performance, so can reproduce even the recorded noise on a CD (which you usually do not hear because instruments play a lot louder). A Xonar DX should be pretty close to that and only costs € 65 here.
 
So a good enough DAC is usually the smallest problem in a hi-fi chain.
 

 Amplifier: Initially it only serves two purposes: 1. Amplify the signal to make it louder. 2. Properly feed the later load (your headphones). There are difficult and easy to drive headphones, and it's something that depends of the frequency you are reproducing. Let's say that the prebuilt amplifier of your phone might be able to drive properly between 3k and 7kHz but it's not able to drive properly in the sub 400Hz region, therefore your music is gonna sound weird and muddy. The better the amplifier the better the sound usually.

1. is voltage gain, 2. is current gain
Depending on the source and sensitivity of your headphones you may not even need voltage gain. In-ears for example will blow up if you feed them 1-2 Volts, many DACs output 2 Volts however.. not to mention what would happen to your hearing.
 
The better the amplifier, the less it will change the signal (less noise, lower distortion, flatter frequency response etc.). A DAC is actually trying to achieve the same - convert the digital signal into an analog signal that is as close as possible to the theoretically reconstructed signal. This works for most DACs, again, pretty well, up to some point (20+ kHz for CDs for example).
 

Initially both the amplifier and the DAC should be completely transparent, that means that they should not boost any frequency nor modify their responses (that is what an objective DAC, amp does). In the reality the world is far from being perfect, which means that you are gonna be altering the signal by passing it through several steps. That's why everybody talks about warm or bright DAC's / amps, and even more, some people try to find some sinergy between their headphones and gears (this is something that depends on you, and on what you give the highest emphasis in your equipment).

The idea of synergy is highly problematic. Imho, it's more of satisfying an urge to buy new audio stuff than going at it from an angle that really focuses on an improvement in sound quality.
 
Lots of what you read in reviews about some electronics being bright/dark/warm/cold etc. is wrong. For example, a reviewer used to an amp with high output impedance (like a receiver's headphone jack) will say a more accurate amp with 0 ohm output will sound bright. It doesn't, it's flat. If anything, you could say it has less bass boost and "sounds" more accurate with a dynamic headphone.

 

[Ashade]

Every addition is welcome! The problem with audio is that you can be talking for hours!

I agree with everything you said as well.

 

[senorx12562]

I guess my question was not very clear. If the only effect an amplifier can have on recorded music is to play it back at a higher volume, then the effect on the sound of my music that I noted when using my E07K is imaginary, because I'm still listening to music at the same volume, I just thought I heard more of a sense of "space" between the components of the music, along with more "directionality" with respect to the various instruments /voices than without the amp. I definitely am not in the subjectivist camp of the ongoing debate in audio between measurement and just listening, so I have no interest in spending any money on a perceived but not real improvement in sq. I don't need more volume, unless that also brings better sq because of the additional "headroom." Probably heresy around here, but so be it. So, is my sq maxed out? I'd be more than happy to keep what I've got and spend my $ on bourbon.

 

[xnor]

E07k seems like a very good little device especially for IEMs. Just wondering why your laptop doesn't recognize it.

 

[stv014]

  If the only effect an amplifier can have on recorded music is to play it back at a higher volume

 
That is not necessarily true, especially if you are using IEMs from a computer onboard audio output, which is likely to have a high output impedance, a relatively high noise floor (low dynamic range at a volume that is bearable with sensitive IEMs), and possibly undersized output capacitors. Factors like these can affect the sound regardless of the available maximum power, and, contrary to popular belief, they can affect low impedance headphones.
 

  then the effect on the sound of my music that I noted when using my E07K is imaginary, because I'm still listening to music at the same volume

 
It is not easy to judge absolute loudness by ear, especially if the switching time between the devices is not very short (I mean less than a second). To really compare amplifiers at matched levels, you need to measure the output voltage with the load (headphones) connected.

 

[senorx12562]

Ironically, my full size cans sound worse than my iems directly from my laptop. They just won't get loud enough. The iems sound ok, but as I said, its not a lack of volume. I don't have ready access to the specs for my laptop now so I don't know any particulars, although it was a "media/entertainment" laptop when I bought it (Sony VAIO) so it might be a little better than average in the audio realm, but then again, maybe not. Most of my files are 320kbps MP3 files. So far, reripping them at 320 instead of 128 has done the most for the sound of my music.

 

[stv014]

If low impedance and reasonably efficient full size headphones are not loud enough from the laptop, then it quite likely has a high output impedance (something like 75 Ω), which reduces the output voltage when driving a low impedance load. It also explains bad frequency response with IEMs like the Westone UM1 or UM3X that have significant impedance variations depending on the frequency.

 

[Ashade]

​

I guess my question was not very clear. If the only effect an amplifier can have on recorded music is to play it back at a higher volume, then the effect on the sound of my music that I noted when using my E07K is imaginary, because I'm still listening to music at the same volume, I just thought I heard more of a sense of "space" between the components of the music, along with more "directionality" with respect to the various instruments /voices than without the amp. I definitely am not in the subjectivist camp of the ongoing debate in audio between measurement and just listening, so I have no interest in spending any money on a perceived but not real improvement in sq. I don't need more volume, unless that also brings better sq because of the additional "headroom." Probably heresy around here, but so be it. So, is my sq maxed out? I'd be more than happy to keep what I've got and spend my $ on bourbon.

Let's put it this way: The amp is not going to make your crappy recordings sound better, but if the internal amp of your laptop is not powerful enough to drive your headphones/IEMs properly it will make the music sound better by driving them better. The result may be better instrument separation, larger sound stage and basically everything you described above.

Now, if you get the internal DAC of the E07K to be recognized by your laptop, the sound quality will improve even more.

All of thia is gonna depend of course on the limitations of your headphones / IEMs as well. By the way, the difficulty of the headphones to be driven properly not always relates with the impedance. For example Q701 and FA003 have pretty similar impedance and while the second one is really easy to drive the first one requires something like the O2 to be properly driven.

 

[senorx12562]

None of my headphones are hard to drive, especially not my iems of course, and I don't listen to my computer directly that often, other than via a bluetooth soundbar/sub combo. When I listen to music via 'phones its usually from one of my portable devices, even at home. Maybe that's because the sound quality on the laptop isn't as good as the devices, although it still isn't as bad as what people here always say about their computers' sq. I was hoping that the O2 would give me a desktop that would provide better sound with my portable devices when I was at home, especially with headphones, and also improve the sound out of my laptop. It's all good, I just have a thing about audio gear.

 

[Sonic Atrocity]

Hey everyone, Mr. Fidelity here. I'm a freak about fidelity (neutral frequency response (or in other words, "flat"), very high transparency, accurate instrument positioning, accurate sound staging, etc. 
 
Anyhow, I haven't read the whole thread, as it is 26 pages long, but every post I've read thus far says the amp portion of this product is transparent. Okay, great! That's awesome. Hence I'm interested! However, I am curious, is the DAC portion of this product transparent/neutral as well? If not, then I was thinking I would purchase the amp portion on it's own, and a different DAC to go with it. 

 

[stv014]

However, I am curious, is the DAC portion of this product transparent/neutral as well?

 
I do not have one, but it is claimed to be transparent. However, DACs can be transparent or very close to transparent (save for a small number of "golden eared" listeners) at a fairly low price now, so it is not an outstanding feature for a $150 USB DAC without any additional features to be neutral and transparent, it just has measurements made with professional equipment published, which is often not the case for other products.

 

[adydula]

The ODAC is extremely transparent.
A.

 

[miceblue]

I think this DAC is more transparent.

http://hobbyaudios.blogspot.com/2013/08/transparent-box-for-dac-akm4396.html
 
On a more serious note, what defines transparency in audio? The O2 was shown to be transparent against the DAC1PRE, but that's it. That does not necessarily mean it's transparent. For all we know, the DAC1PRE could be really coloured, which is analogous to saying the O2 is really coloured.
 
Likewise for the ODAC. What makes it transparent? From what I recall, they didn't do any [insert sound science only term] tests with the ODAC.

 

[Sonic Atrocity]

Hahahahhaa, I'm sitting in class, listening to a lecture on Kantian ethics, and I almost laughed out loud at the photo you posted, hahaha. Indeed, he who shall not be mentioned has not tested this product, and therefore you pose a good question. 
 
In my personal opinion, neutrality/transparency/fidelity is a concept that should be verified within a product on it's own, independent of the status of fidelity in other products. 

 

[adydula]

This one is more transparent than your plexiglass one....your plexiglass isnt totally clear on all the edge contact points.....
This has got to affect the transparecy dont you think?
Not to mention all the AC floating around next to the circuitry....yuck!