[Vader2k]

  If you like your Marantz for the Dolby processing that's fine. The O2 amp being very neutral or transparent should not add or detract from what u put into is within its design.
 
Most likely the damping factor of the Marantz is helping cause the bass to what it is etch..
 
You could just try an o2 and odac to see how they compare.
 
Good Luck
Alex

 
Yeah, I suppose hearing the X1s separate from the Marantz for comparison wouldn't be a bad idea, just to be able to hear how much difference there is in the bass in the first place.
 
Thanks for the help.

 

[hekeli]

  Hmm.. well, I have never experienced clipping or distortion with the O2/ODAC combo, despite needing to use high gain to drive my LCD 2's... but then, I don't go for earsplitting. I also usually use software to attenuate recordings that butt up against the redline (bad mastering).
 
The 02's THD chart stays very low - even the worst performing chip stays under .01, pretty much right up until you get to where is will clip... I don't think audible distortion is the amp at that point, but either the headphones or the recording... 

 
The O2 gain structure has been discussed in numerous posts and threads, yet all the time there's some misunderstanding? Someone should make a clear example FAQ page somewhere for ready quoting... the main point is that distortion happens _before_ the pot. If you "blast" a ~2 volt source like ODAC and use 6.5x gain, you might easily go into distortion (2 x 6.5V = 13V, well over 7V... of course real music is not continuous full blast sinewave but yeah "hot" music might do it). So regardless how "loud" you play, it's still distorted even if listening pot in whisper quiet position. Depending on how experienced one is, light <10% distortion might go easily unnoticed if not paying attention..
 
The gain should be chosen by the source you intend to use and only that. For ODAC 1x/3.0-3.5x is around optimal, enabling all audio extremes (while never being able to clip). Of course you can have 6.5x if you lower the volume in your player/OS accordingly (someone posted some volt measurements here for ODAC and Windows volume control I think..)... but it would only make sense if you intend to sometimes use poor source like portables outputting just 1 volt and need the full ~7V output. Even playing "quiet classical" is not a sane reason for overdoing it, since the peaks would still clip. If there are no "0dBFS peaks", well obviously your file should be normalized/replaygained louder then..

 

[Aikanaro]

love how this combo just amplifies. no frills, you get your money's worth. difficult to beat at that price range imo

 

[liamstrain]

   
The O2 gain structure has been discussed in numerous posts and threads, yet all the time there's some misunderstanding? Someone should make a clear example FAQ page somewhere for ready quoting... the main point is that distortion happens _before_ the pot. If you "blast" a ~2 volt source like ODAC and use 6.5x gain, you might easily go into distortion (2 x 6.5V = 13V, well over 7V... of course real music is not continuous full blast sinewave but yeah "hot" music might do it). So regardless how "loud" you play, it's still distorted even if listening pot in whisper quiet position. Depending on how experienced one is, light <10% distortion might go easily unnoticed if not paying attention..
 

 
Thank you for clarifying. Some pots control from the input stage, others are on the output. 

 

[Medaud]

If you want to mod the gain, how difficult is it to remove the resistors and solder on some new ones? I haven't soldered since secondary school.

 

[miceblue]

Hi, i got the Geek Out, and read that it's similar to the ODAC/02 , my question is how similar, and if there is any point in getting the ODAC/O2?

I find that the Geek Out is a bit better than the ODAC/O2 overall in terms of sound quality, but if you prefer having separate modules like the ODAC and O2, then I would recommend the Objective combo for that. I'll probably still use the ODAC for the RCA and 3.5 mm interconnect outputs, but I've been using the Geek Out more than the Objective combo recently. Having the ability to play high resolution masters natively, as well as DSD, is a plus too.

 

[adydula]

The gain in the o2 can easily be set with by clipping resistors or changing their values, no transistors...
 
A.

 

[Medaud]

  The gain in the o2 can easily be set with by clipping resistors or changing their values, no transistors...
 
A.

 
Sorry, my bad, resistors. To change their values (other than to 1x), you would have to remove them and solder on some new ones, correct?

 

[adydula]

Yes,
 
The gain resistors are identified in the BOM....for values from 1x to 12x.....
 
 
R17, R19, R21, R23
 
Take a look over there.
 
Alex

 

[barihunk]

   
The O2 gain structure has been discussed in numerous posts and threads, yet all the time there's some misunderstanding? Someone should make a clear example FAQ page somewhere for ready quoting... the main point is that distortion happens _before_ the pot. If you "blast" a ~2 volt source like ODAC and use 6.5x gain, you might easily go into distortion (2 x 6.5V = 13V, well over 7V... of course real music is not continuous full blast sinewave but yeah "hot" music might do it). So regardless how "loud" you play, it's still distorted even if listening pot in whisper quiet position. Depending on how experienced one is, light <10% distortion might go easily unnoticed if not paying attention..
 
The gain should be chosen by the source you intend to use and only that. For ODAC 1x/3.0-3.5x is around optimal, enabling all audio extremes (while never being able to clip). Of course you can have 6.5x if you lower the volume in your player/OS accordingly (someone posted some volt measurements here for ODAC and Windows volume control I think..)... but it would only make sense if you intend to sometimes use poor source like portables outputting just 1 volt and need the full ~7V output. Even playing "quiet classical" is not a sane reason for overdoing it, since the peaks would still clip. If there are no "0dBFS peaks", well obviously your file should be normalized/replaygained louder then..

 
+1 - the documentation is still out there, if one bothers to read it. It's dense reading but it's there.
 
I would venture to say though that if your music is pretty varied though, and *if* you use replaygain, I think 2x/6.5x is still a workable gain. I find it to be quite useful for my replaygain-ed library since rather than "adding" gain what it does is reduce gain (make louder tracks softer) so I rarely if ever hit clipping even at 6.5x gain. (even the 2.0V ODAC may not reach 2.0V at 100% on the computer because of the negative gain applied by replaygain)
 
The other issue is that most folks with pre-built O2/ODACs have the lower power 12v 200mA AC adaptor, as opposed to the slightly higher end 16v 400mA adapter alternative in the BOM. 
Kind of wish though that the O2 included some sort of clipping indicator to satisfy my OCD tendencies though.

 

[wigglepuff]

How would the Philips X1  sound on this compared to using a fiio e07k or e17? I'm looking for an amp that will output clear and neutral sound (given the music played isn't bass intensive also) without making the bass bloat or boomy.  I currently only have the e07k and the bass is a little bit better compared to the onboard alc889 which sounded all over the place and made my ears hurt even on low volume.
 
I could just use the e07k's dac and use the O2 as amp but I can't find an O2 for testing in my area. Do I also need the l7 cable for the 07 and o2amp to work?

 

[Medaud]

   
+1 - the documentation is still out there, if one bothers to read it. It's dense reading but it's there.
 
I would venture to say though that if your music is pretty varied though, and *if* you use replaygain, I think 2x/6.5x is still a workable gain. I find it to be quite useful for my replaygain-ed library since rather than "adding" gain what it does is reduce gain (make louder tracks softer) so I rarely if ever hit clipping even at 6.5x gain. (even the 2.0V ODAC may not reach 2.0V at 100% on the computer because of the negative gain applied by replaygain)
 
The other issue is that most folks with pre-built O2/ODACs have the lower power 12v 200mA AC adaptor, as opposed to the slightly higher end 16v 400mA adapter alternative in the BOM. 
 
 
Kind of wish though that the O2 included some sort of clipping indicator to satisfy my OCD tendencies though.

 
Argh, it's so difficult to figure out the best gains when you have to take so many things into consideration. :/ I ordered a 1x/5x config, but reading the last few posts was just about to attempt to change my order to 1x/3x. Then you wrote about replaygain, which I use too. So I guess suddenly 1x/5x would be fine with me? Even more so if I change to a pair of 300ohm headphones in the future?
 
lol, anyway, I think I'll just wait for my 1x/5x O2/ODAC to arrive and see how it goes. Worst comes to worst I'll change the gain resistors.

 

[adydula]

My ODA has a clipping led.
 
The gains are 1x, 2x, 4x 6x....I only see clipping on 4x and 6x with hot titles -10 to -14 db or so....I can stop the clipping by lowering the player volume a bit, using replay gain in the player and or use a lower gain setting. I most always use 1x and sometimes 2x....never a need with my Beyer T90s to go to any higher gain settings.
 
Alex

 

[Cankin]

With ODAC as source and power adaptor, I use only gain of 1x with my HD800. Volume knob at 10 o'clock even with quiet classical recording. 
 

   
Argh, it's so difficult to figure out the best gains when you have to take so many things into consideration. :/ I ordered a 1x/5x config, but reading the last few posts was just about to attempt to change my order to 1x/3x. Then you wrote about replaygain, which I use too. So I guess suddenly 1x/5x would be fine with me? Even more so if I change to a pair of 300ohm headphones in the future?
 
lol, anyway, I think I'll just wait for my 1x/5x O2/ODAC to arrive and see how it goes. Worst comes to worst I'll change the gain resistors.

 

[barihunk]

   
Argh, it's so difficult to figure out the best gains when you have to take so many things into consideration. :/ I ordered a 1x/5x config, but reading the last few posts was just about to attempt to change my order to 1x/3x. Then you wrote about replaygain, which I use too. So I guess suddenly 1x/5x would be fine with me? Even more so if I change to a pair of 300ohm headphones in the future?
 
lol, anyway, I think I'll just wait for my 1x/5x O2/ODAC to arrive and see how it goes. Worst comes to worst I'll change the gain resistors.

 
IMHO ordering with 1x gain is not the best choice, for the simple reason that you can just clip whichever resistor pair you want to achieve 1x gain (i.e. removing the gain resistors). Better to order something higher then clip or de-solder the resistors if you don't want the high gain. I have a custom built O2 from when the design first debuted and can easily swap gain resistors, so I've gone anywhere from 2x/6.5x to 1x/4x then now back to 1x/6.5x - 1x works great for sensitive phones, 6.5x works pretty well for my HE-560. 
 

IIRC a good way to change volume is to just leave the O2 at whatever gain you determine, at max volume, and change the volume in software, where you can change volume in 24/32bits.