[Psalmanazar]

  I'm not a fan of starting new threads for the sake of it, so I'll post these ramblings here.
 
Need someone to talk me out of getting the O2+ODAC to replace my FiiO E10K, which is what currently powers my Fidelio X2.  It'd work out at about 3x the price of the E10K and I'm unsure it would provide a noticeable increase in sound quality.
 
DISCLAIMER: I'm not a headphone collector, can't hear above 15khz, 90% of my listening is TV/movies, and I have trouble noticing a difference from onboard ALC892 compared to the E10K.
 
Talk me down!
 
EDIT: I only just discovered that both the E10K and ODAC RevB share the same PCM5102A chip.

Save your money and don't worry about it until you get new headphones or listen to more music. A case of beer or bottle of liquor would be a more enjoyable purchase for you now. You know it to be true!

 

[Smugsie]

  I'm not a fan of starting new threads for the sake of it, so I'll post these ramblings here.
 
Need someone to talk me out of getting the O2+ODAC to replace my FiiO E10K, which is what currently powers my Fidelio X2.  It'd work out at about 3x the price of the E10K and I'm unsure it would provide a noticeable increase in sound quality.
 
DISCLAIMER: I'm not a headphone collector, can't hear above 15khz, 90% of my listening is TV/movies, and I have trouble noticing a difference from onboard ALC892 compared to the E10K.
 
Talk me down!
 
EDIT: I only just discovered that both the E10K and ODAC RevB share the same PCM5102A chip.

I'm sorry sir, I'll probably do the opposite.

My condolences to your wallet.

 

[Hammy]

  Save your money and don't worry about it until you get new headphones or listen to more music. A case of beer or bottle of liquor would be a more enjoyable purchase for you now. You know it to be true!

 
I do suspect this to be true, but I bought the E10K specifically for the HD598 and now suspect the synergy (is that a thing? ) with the X2 may not be the best.
 

 
I'm sorry sir, I'll probably do the opposite.

My condolences to your wallet.

 
I can be swayed either way at the moment, although finding out they share the same DAC chip was kind of worrying.  I'm assuming the amp is much more powerful in the O2 and the ODAC implements things better on the DAC side, but I kind of suspect I'd be mostly paying for numbers on a sheet rather than lovely feelings coming in my ears.

 

[lvince95]

   
I do suspect this to be true, but I bought the E10K specifically for the HD598 and now suspect the synergy (is that a thing? ) with the X2 may not be the best.
 
 
I can be swayed either way at the moment, although finding out they share the same DAC chip was kind of worrying.  I'm assuming the amp is much more powerful in the O2 and the ODAC implements things better on the DAC side, but I kind of suspect I'd be mostly paying for numbers on a sheet rather than lovely feelings coming in my ears.

The X2 doesn't scale at all. The E10K is enough.
 
Source: Didn't notice much of a difference from my MBP Retina vs the O2+ODAC when I had the X2.

 

[raoultrifan]

I had some time to spare with my beloved O2 this weekend, so while trying to find what's my O2's max. non-clipping output voltage I was able to get a decent output voltage of 7.4V RMS (with dummy load of 500ohms resistors + original Beyers cable serialized, instead of headphones) before starting to clip and without any sort of strange spikes or oscillations.
 
So, while my 3 years old kid was spilling water inside a power stripe's outlet (thank's God of the 30mA differential safety) and he was unscrewing all the screws from a wooden IKEA chair (for all these screws I applied a 10-12nM of torque when I built this chair; I had no idea that kids today have such a force to unscrew'em) I did few mods during this weekend:
- 1) Changed the gain resistors from infinite/1Kohm (corresponding to 1X/2.5X) to 2.5Kohm/516ohms (corresponding to 1.6X/3.78X). I did some "custom resistors" of about 516ohms by serializing 274ohms + 242ohms resistors that I had in stock; this corresponds to a real gain of about 3.78X and an output voltage of about 7.3V RMS (a bit less than max. non-clipping voltage of 7.4V RMS, just to be sure clippings will never occur when ODAC is connected, even with loud and highly compressed music). Perhaps some of you might still say that a gain of 3.78X is too much and voltage gain will clip, but with my ODAC XL connected to O2 and 0dB sinewaves applied (taken from audiocheck.net) there's no clipping at all. Looks like my ODAC can output 1.921V RMS when sinewaves are applied; I have tried 20Hz, 32Hz, 1KHz, 16KHz, 20KHz and I get no clipping, no roll-offs, no oscillations, no strange FFT harmonics, no THD >0.1% (checked with my PicoScope 2204A).
 

​

 
- 2) Added 2 x 1uF film capacitors immediately after the 2 regulating diodes from power input plug. These 2 caps should decrease any possible noise coming from the mains.

​

 
- 3) Added 2 x 10uF/25V AVX tantalums on output regulators, to further decrease the ripple.
- 4) Added 2 x 47uF/35V Nichicon KA and 2 x WIMA 0.1uF/100V for decoupling the input stage OPAMP (LME49720).
- 5) Added 2 x 47uF/35V Nichicon KA for each of the 2 output buffers for decoupling purposes (NJM4556A).

​

 
 
Did I gained anything?
- Besides a lot of fun, I was able to decrease ripple & noise from 2.3mV p-p to 0.747mV p-p, measured directly on each regulator output and also on OPAMPs +/-V rails. That's a good ripple decrease, though it should probably not be noticed on headphones out, because O2's OPAMPs already have a good ripple reduction inside (PSRR & CMRR of about 90-100dB).
- Soundstage increased a little bit, though this is a subjective impression that I'm going to test it soon by A/B'ing.
- OPAMPs rolling should be easier now with additional decoupling caps used.
 
Note: The tested O2 has LME49720 on input stage and 2 x NJM4556A as buffers. All 3 OPAMPs have heatsinks on top, glued with Arctic Alumina compound. There are 2 power plugs in front and back, 2 headphone jack: 3.5mm and 6.3mm on front and RCA outputs on the back. I'm also using original 9V/300mAh batteries and original 15V/500mAh power adapter.
 
P.S.: Looks like the way I arranged one of tantalums was not good, because I couldn't close the case, so I need to move it a few mm away from the edge of the PCB.

​  ​

​  ​

 

[MrMateoHead]

  I'm not a fan of starting new threads for the sake of it, so I'll post these ramblings here.
 
Need someone to talk me out of getting the O2+ODAC to replace my FiiO E10K, which is what currently powers my Fidelio X2.  It'd work out at about 3x the price of the E10K and I'm unsure it would provide a noticeable increase in sound quality.
 
DISCLAIMER: I'm not a headphone collector, can't hear above 15khz, 90% of my listening is TV/movies, and I have trouble noticing a difference from onboard ALC892 compared to the E10K.
 
Talk me down!
 
EDIT: I only just discovered that both the E10K and ODAC RevB share the same PCM5102A chip.

 
You don't need more power, and your headphone performance will not improve appreciably on the new setup. That should be sufficient. If anything, you'll be annoyed unless you stayed on unity gain / 2.5x because you can barely twist the dang volume knob out of its channel-imbalance range.
 
Unless you can't routinely playback your program materials at a volume you want, or can hear a difference between your available DACs, you would be straight up wasting your money.
 
When and if you start listening to more music, and in particular get headphones with big impedance swings or that are inefficient, you will be glad to have the O2's power. Until then, you are just fantasizing about everything being "better" because you spent more and have more power. Its not true.
 
What started you on the path to upgrading your Amp/DAC in the first place? Because I can tell you that in my experience so far, low-impedance headphones with mild impedance swings do not improve drastically going from mediocre to "awesome" amps. If you want a different sound, it is best to look for new cans!

 

[Hammy]

   
You don't need more power, and your headphone performance will not improve appreciably on the new setup. That should be sufficient. If anything, you'll be annoyed unless you stayed on unity gain / 2.5x because you can barely twist the dang volume knob out of its channel-imbalance range.
 
Unless you can't routinely playback your program materials at a volume you want, or can hear a difference between your available DACs, you would be straight up wasting your money.
 
When and if you start listening to more music, and in particular get headphones with big impedance swings or that are inefficient, you will be glad to have the O2's power. Until then, you are just fantasizing about everything being "better" because you spent more and have more power. Its not true.
 
What started you on the path to upgrading your Amp/DAC in the first place? Because I can tell you that in my experience so far, low-impedance headphones with mild impedance swings do not improve drastically going from mediocre to "awesome" amps. If you want a different sound, it is best to look for new cans!

 
Yes, if I had gone down this path it would have been the 1 / 2.5x gain settings for me.  I am not trying not to "fantasize", I'm just looking for opinions from more knowledgable people than myself.
 
I appreciate you have not experienced low-impedance headphones scaling well, but some owners of the X2 have the opposite opinion, and I simply wanted to investigate whether there were better options out there for me than the E10K. 
 
I'm very happy with the volume levels from the E10K, and thanks to you guys I think I've been brought back from the edge of the abyss... for now.

 

[lvince95]

Yes, if I had gone down this path it would have been the 1 / 2.5x gain settings for me.  I am not trying not to "fantasize", I'm just looking for opinions from more knowledgable people than myself.

I appreciate you have not experienced low-impedance headphones scaling well, but some owners of the X2 have the opposite opinion, and I simply wanted to investigate whether there were better options out there for me than the E10K. 

I'm very happy with the volume levels from the E10K, and thanks to you guys I think I've been brought back from the edge of the abyss... for now.

As long as you have a clean source (which the E10K provides), it's enough for the X2 really.

Alternavely you could always get the O2+ODAC to remove your doubts and regret it at the same time :S

 

[Alec246]

I have a ODAC already. Just got the amazing HD600. I wonder if getting the O2 for AMP is the best move now, or should I focus on a better DAC+AMP combo. What do you guys think?

 

[cityle]

  I have a ODAC already. Just got the amazing HD600. I wonder if getting the O2 for AMP is the best move now, or should I focus on a better DAC+AMP combo. What do you guys think?

I would strongly recomment to have an amp with the HD600 if you don't have already an amp (you know, it's a 300 ohms phones). I've read good comments on pairing the HD600 with the O2, but you may want to do some more investigation. Personnaly, I would go for the O2 and the odac as I have this setup and I love it and I want the less coloration possible.

 

[Alchemist007]

What are the O2+ODAC's limits or how would you determine them? Would they run an LCD-4 and why or why not? Just an educational question, I don't have the $$ for such a headphone!

 

[MrMateoHead]

  What are the O2+ODAC's limits or how would you determine them? Would they run an LCD-4 and why or why not? Just an educational question, I don't have the $$ for such a headphone!

Data on the O2 is already on the Internet and is easy to find. The max output is around a half-watt (500-700 mWs) at around 50 Ohms. At very low distortion, it pretty reliably supplies 100-200 mWs but I am working off memory so don't hold me to that.
 
The "limit" IMO is all about how loud you are trying to go, as determined by the efficiency of the headphone and the available low-distortion power. Given that even some of the most inefficient phones can put out well over 90 dB with 1 little mW (or indeed more like 100 dB), the O2 is more than enough power for most cans played back at non-ear destroying levels. That would be true of any amp with similar power on tap.
 
The LCD-4 claims efficiency of 100 dB / 1 mW. 100 dB is well into ear-damage range. But to get to concert like levels, you would need about 10 times that power or 10 mWs. Just because the thing is rated to survive 15 watts doesn't mean I'd attempt that on my head! Sheesh. Audeze claims that "optimal" power is in the 1-4 watt range, which may be true. But just on the basis of power-for-spl that would seem like complete and total overkill. But to be fair, depending on the type of recording and the maximum dynamic range of said recording, more or less power may be needed than that first fraction of a mW. Ditto if your source to the amp is "weak" (1 V or less). In fact, that is why, for example, classical music (or a movie) tends to need "more power" than pop. The wider swings of the music require the amplifier to supply more peak power during crescendos and so on.
 
It is a good idea to consider the ability of any speaker to playback high levels with low distortion or compression (say less than 10%). The speaker is more likely the "limiting factor" in terms of sound quality - not necessarily the amp. Many can handle high power but my ears tell me that I am going from enjoyment to congestion / pain when SPL starts to average more than about 80 dB. I like to listen closer to 60-70 dB most days anyhow. But I'd be surprised if the LCD-4, or any headphone for that matter, could playback 120 dB or more full-range without being totally distorted.
 
Hope that feeds your curiosity!

 

[jimbop54]

After reading all the great reviews, I bought an O2/ODAC and then discovered that I can't use it directly with my iphone or ipad. So now I have a powered USB hub and and the extra power and connection cables littering my desk, when I was expecting that this would be nice 1-box system.
 
Is this common with other dacs/amps? Are there any other solutions?
 
JD

 

[WilliamLeonhart]

  After reading all the great reviews, I bought an O2/ODAC and then discovered that I can't use it directly with my iphone or ipad. So now I have a powered USB hub and and the extra power and connection cables littering my desk, when I was expecting that this would be nice 1-box system.
 
Is this common with other dacs/amps? Are there any other solutions?
 
JD

From what I know, yes it is in most cases. With a very few exceptions (the Cayin C6, also it's very meh), you'll almost always have to buy at least the Camera Kit for iPhone/iPad. The JDS C5D requires it, for example. If you're luckier, the DAC/amp passed "MFI" certification by Apple, so you'll only need a Lighting-usb cable.
Then, if the DAC require more power, you'll have to buy a hub too. Which is the case with the ODAC (notice that the O2 has nothing to do here).
 
But anyway the O2 ODAC sounds definitely better than all the other DAC/amp in the price range, if neutral, accurate sound is what you're after. It's a matter of convenience vs. SQ, you see.

 

[adydula]

Hey Guys/Gals....I finally completed my inverting O2 type headphone amplifier, its in the final case, new engraved front panel from Front Panel Express and using an ODAC.
 
If your interested check it out, many pix etc:
 
http://www.head-fi.org/t/793384/an-inverting-version-of-the-o2-headphone-amp-vs-the-original-diy-at-its-best/15#post_12287235
 
Alex