[ieee754]

Is there any quality loss if I connect O2 with another amp? I'd like to use my ODAC but it's in combo with O2 and I don't want to mess with internal electronics.

 

[AsianBatman]

If your amp section is powered off, the amp line out works as a dac only. There should be no quality loss. 

 

[ieee754]

  If your amp section is powered off, the amp line out works as a dac only. There should be no quality loss. 

Does it really work? After turning off amp I don't hear anything from headphones. Shouldn't it play at a very low volume?

 

[Solrighal]

Does it really work? After turning off amp I don't hear anything from headphones. Shouldn't it play at a very low volume?

No. If it does you're about to become a billionaire.

 

[ieee754]

It works! But I had to connect headphones to line-in of the amp, and it plays only at low/moderate level. Why do I need O2 then? 

 

[AsianBatman]

  It works! But I had to connect headphones to line-in of the amp, and it plays only at low/moderate level. Why do I need O2 then? 

 
Well, my stand alone odac also works when I plug in my headphones, but it does not have nearly enough power to actually drive headphones to optimal listening levels. I find that my iems do well with the ODAC alone and adjusting the volume in windows to 100% produces a decent volume. Which amp are you planning to use with your DAC?

 

[ieee754]

   
Well, my stand alone odac also works when I plug in my headphones, but it does not have nearly enough power to actually drive headphones to optimal listening levels. I find that my iems do well with the ODAC alone and adjusting the volume in windows to 100% produces a decent volume. Which amp are you planning to use with your DAC?

I used Sennheiser Momentums which are pretty efficient and the volume level of ODAC is listenable, but it lacks bass a bit. I'm not sure about new amp, I'm interested in getting Hifiman headphones (now waiting to see reviews and measurements of HE-560) which require a lot of power so I'm asking just in case O2 was not enough. Do you know any O2-like (in terms of transparency) amp that could drive even HE-6?

 

[AsianBatman]

  I used Sennheiser Momentums which are pretty efficient and the volume level of ODAC is listenable, but it lacks bass a bit. I'm not sure about new amp, I'm interested in getting Hifiman headphones (now waiting to see reviews and measurements of HE-560) which require a lot of power so I'm asking just in case O2 was not enough. Do you know any O2-like (in terms of transparency) amp that could drive even HE-6?

 
Unfortunately, I do not have any experience with Hifiman products aside from my short lived possession of the HE-300 (sold it). As far as amps go, I only own the O2 and NFB-12.1. Both are efficient to drive HD600 and Denon 2k. Hopefully someone else may point you in the right direction in terms of amps for HE-6. 

 

[Solrighal]

Unfortunately, I do not have any experience with Hifiman products aside from my short lived possession of the HE-300 (sold it). As far as amps go, I only own the O2 and NFB-12.1. Both are efficient to drive HD600 and Denon 2k. Hopefully someone else may point you in the right direction in terms of amps for HE-6. 

That's interesting that you're O2 was capable of driving the HD600. Do you know what gain setting that was with? I ask because I quite fancy a pair of HD600's in future.

 

[ieee754]

   
Unfortunately, I do not have any experience with Hifiman products aside from my short lived possession of the HE-300 (sold it). As far as amps go, I only own the O2 and NFB-12.1. Both are efficient to drive HD600 and Denon 2k. Hopefully someone else may point you in the right direction in terms of amps for HE-6. 

Ok, thanks anyway, I didn't know that this is possible to use ODAC directly from the combo.
 
By the way, is there any reason to think that O2 won't be able to drive headphones like HE-500 even at high volume? I did the math and it seems that O2 with 613mW at 33ohms headphone impedance is able to drive any headphone with efficiency above 87.5 dB/mW to peak SPL of 115dB without clipping, here is how I calculated it:
 
E - headphone efficiency in dB
P - power from amplifier (for O2 it's 613)
 
10^((115 - E)/10) = P
115 - E = 10 * log(P)
E = 115 - 10 * log(P) = 115 - 10 * log(613) = 115 - 27,87 = 87,13
 
I was told in another thread that O2 can't drive HE-500 at high volume, but it seems that to reach 115 SPL only 398mW is required, is there some property of O2 that makes it worth getting better amp?

 

[AsianBatman]

That's interesting that you're O2 was capable of driving the HD600. Do you know what gain setting that was with? I ask because I quite fancy a pair of HD600's in future.

 
I clipped my O2 myself to 1x/2.5x gain and use 1x gain with my HD600. I am among many that find the O2 sufficient in driving the HD600. Although I do prefer my NFB 12.1 for the HD600 since it adds a little darkness to the sound. 
 

  Ok, thanks anyway, I didn't know that this is possible to use ODAC directly from the combo.
 
By the way, is there any reason to think that O2 won't be able to drive headphones like HE-500 even at high volume? I did the math and it seems that O2 with 613mW at 33ohms headphone impedance is able to drive any headphone with efficiency above 87.5 dB/mW to peak SPL of 115dB without clipping, here is how I calculated it:
 
E - headphone efficiency in dB
P - power from amplifier (for O2 it's 613)
 
10^((115 - E)/10) = P
115 - E = 10 * log(P)
E = 115 - 10 * log(P) = 115 - 10 * log(613) = 115 - 27,87 = 87,13
 
I was told in another thread that O2 can't drive HE-500 at high volume, but it seems that to reach 115 SPL only 398mW is required, is there some property of O2 that makes it worth getting better amp?

 
To be honest, that math goes over my head. Been awhile since I've dealt with that kind of stuff, but I'm assuming that ohm swings cause by different frequency output causes a fluctuation in output mW? Best analog I can think of is subwoofer amps for cars. Just cause an amp is rated for 1000 watt doesn't mean it's better than an amp rated for 500 watt, in this case you would want to look at the RMS output an amp has and out steady the wattage is when the sub hits at different volumes. I could be completely wrong. Just from following the Hifiman thread, I don't see many O2s used for HE-500. 

 

[Solrighal]

I clipped my O2 myself to 1x/2.5x gain and use 1x gain with my HD600. I am among many that find the O2 sufficient in driving the HD600. Although I do prefer my NFB 12.1 for the HD600 since it adds a little darkness to the sound.

That's good to know. I use 1x/3x gains so I'd get away with it. Thanks for the info.

 

[miceblue]

 

Unfortunately, I do not have any experience with Hifiman products aside from my short lived possession of the HE-300 (sold it). As far as amps go, I only own the O2 and NFB-12.1. Both are efficient to drive HD600 and Denon 2k. Hopefully someone else may point you in the right direction in terms of amps for HE-6. 

Ok, thanks anyway, I didn't know that this is possible to use ODAC directly from the combo.

By the way, is there any reason to think that O2 won't be able to drive headphones like HE-500 even at high volume? I did the math and it seems that O2 with 613mW at 33ohms headphone impedance is able to drive any headphone with efficiency above 87.5 dB/mW to peak SPL of 115dB without clipping, here is how I calculated it:

E - headphone efficiency in dB
P - power from amplifier (for O2 it's 613)

10^((115 - E)/10) = P
115 - E = 10 * log(P)
E = 115 - 10 * log(P) = 115 - 10 * log(613) = 115 - 27,87 = 87,13

I was told in another thread that O2 can't drive HE-500 at high volume, but it seems that to reach 115 SPL only 398mW is required, is there some property of O2 that makes it worth getting better amp?

Reaching the right power is one thing, but having sufficient current going through a low-impedance/efficient headphone is another. I don't know the current limitations for the O2's op-amps, but planar magnetic headphones are current-demanding. You might not have the same bass slam as with an amp of higher current output.

 

[AsianBatman]

That's good to know. I use 1x/3x gains so I'd get away with it. Thanks for the info.

Of course the gain depends on your source also. I find that I need higher gain if I use it with my cellphone, and less if I use it with the Odac. How far into the future will this investment be? :]

 

[Solrighal]

Of course the gain depends on your source also. I find that I need higher gain if I use it with my cellphone, and less if I use it with the Odac. How far into the future will this investment be? :]

I'll be using the ODAC as my main source for quite some time yet. I don't know about the Senn's, I'm torn between them and Grado's.