[ProtegeManiac]

  I'm thinking of getting an ODAC with RCA outputs so that I can connect the 3.5mm output to my O2 headphone amp and the RCA outputs to my stereo speaker amplifier.  However, the JDS Labs webpage warns: " Please note that ODAC supports only 1 output; do not use 3.5mm and RCA jacks simultaneously."
 
Why is that?  What would happen if I connect my equipment as described above?  I only intend to have one of the amplifiers on at a time (it wouldn't make a lot of sense to listen to music on the headphones and speakers simultaneously).
 
Thanks

 
Just unplug the 3.5mm if you're using the RCA output. They're less susceptible to wear, given the RCA plugs' design that has them contracting and expanding if pulled out and pushed back in too often, that might scratch the coating.

 

[Zoide]

Just unplug the 3.5mm if you're using the RCA output. They're less susceptible to wear, given the RCA plugs' design that has them contracting and expanding if pulled out and pushed back in too often, that might scratch the coating.

Couldn't I just turn the headphone amp on/off instead of having to plug and unplug the 3.5mm cable?

 

[ProtegeManiac]

Couldn't I just turn the headphone amp on/off instead of having to plug and unplug the 3.5mm cable?

 
The way I understand their note on the site, in order to prevent the meager power supply (USB 5v) from having to output through both sets, one of them is selected somehow. Or worse, it might select RCA output as default. It would really be best to ask JDS Labs for details, but the thing is, on such a small chassis, getting two sets of outputs is already a lot compared to similar DACs. Most of the others only have an SPDIF output (converting the USB signal).

 

[Zoide]

I wrote to JDS Labs and this is what they replied:
 
"It's actually acceptable to connect two devices as long as both have an input impedance of at least 5k. When a device's input impedance is too low (or unknown), ODAC's performance suffers.
 
Behavior remains identical even if the external device is turned off. The fact that it's plugged in means it's placing an impedance load on the ODAC."

 

[ProtegeManiac]

I wrote to JDS Labs and this is what they replied:

"It's actually acceptable to connect two devices as long as both have an input impedance of at least 5k. When a device's input impedance is too low (or unknown), ODAC's performance suffers.

Behavior remains identical even if the external device is turned off. The fact that it's plugged in means it's placing an impedance load on the ODAC."

Ah so it has to do with the impedance, not necessarily just the power. Better check your amps then; who knows both of 'me could be high enough.

 

[adydula]

I did this a few times and it was terrible.....one was a AVR receiver the other was a PC usb ....very noticeable.
 
Alex

 

[mnarwold]

 

So, I finished the new case for the O2 and ODAC.

 

[MaciekN]

I just recieved an ODAC, soldered the output jack, connected it to a hedphone amp and tried A/B against my old wm8716 + cs8414 DAC. Honestly I couldn't tell much difference on my headphones, though I must admit that neither the amp (bravo audio 6n11 tube amp with 32R output impedance) or my headphones (somewhat modded Alessandro MS-1i) are top notch. Anyway I expected to be blown away, or at least that the differences would be obvious considering that ODAC should be a statement DAC when it comes to PC audio...

 

[mcandmar]

Keep listening, the difference will be in what you cant hear.   I have a couple of DACS, DIY CS8416-CS4398, and a CIAudio CS8416-PCM1794 and they all have their own subtle signature but the ODAC is the most revealing, and cleanest of the three.  Not the must fun to listen to, but technically the best.

 

[mnarwold]

OK guys, need some help. After almost a year of faithful duty, my ODAC has added a great deal of noise to my music. Not just a little bit of background noise, but lots of seemingly random noise. Some pops and clicks and hiss and buzz. Sometimes I hear a distant sine sweep up then down. My first thought was to unplug and plug in again, no go. I then tried a powered USB hub, no go. I restarted computer, no go. I uninstalled the driver and let it reinstall, no go. I tried every USB output on my laptop, no go. I took it out of the above wooden case, no go. I tried on another computer, no go. I tried an "electronics cleaner," no go.
 
After building the wooden case it did work.
 
I'm out of ideas and not really looking forward to buying another DAC. Is there something I should try?

 

[MaciekN]

  Keep listening, the difference will be in what you cant hear.   I have a couple of DACS, DIY CS8416-CS4398, and a CIAudio CS8416-PCM1794 and they all have their own subtle signature but the ODAC is the most revealing, and cleanest of the three.  Not the must fun to listen to, but technically the best.

For over an hour I was going back and forth and whenever I thought I had found something my old dac can't do I went back only to hear that it stays on par with the newcomer. Sometimes I spotted the difference first on the old unit and conversely had troubles finding something that odac wouldn't do. There surely is some room for improvement in the testing procedure such as careful level matching, or eliminating differences on the software side (like using kernel streaming or direct sound) but again, I expected the odac to perform noticably better than a dac with obsolete chips. I did mod my old dac ny adding a piwer supply regulator here and there but then I heard it beaten by some mid tier arcam cd player in a speaker set up, so it's not like I had too much faith in my dac when testing against odac. This makes me even more surprised by the intangible and doubtful differences, hope that odac will somewhat improve over time.

 

[mnarwold]

  OK guys, need some help. After almost a year of faithful duty, my ODAC has added a great deal of noise to my music. Not just a little bit of background noise, but lots of seemingly random noise. Some pops and clicks and hiss and buzz. Sometimes I hear a distant sine sweep up then down. My first thought was to unplug and plug in again, no go. I then tried a powered USB hub, no go. I restarted computer, no go. I uninstalled the driver and let it reinstall, no go. I tried every USB output on my laptop, no go. I took it out of the above wooden case, no go. I tried on another computer, no go. I tried an "electronics cleaner," no go.
 
After building the wooden case it did work.
 
I'm out of ideas and not really looking forward to buying another DAC. Is there something I should try?

OK, just to update on what other things I've tried.
 
I've replaced both the usb and the audio cable with no change
I've booted into linux and have the same issue
I actually noticed that the noise began even before the computer booted. Just going into the bios has the noise going.
It doesn't have any noise when plugged into a powered usb hub when the hub isn't plugged into the computer, not sure if that tells us anything.
 
So far I can't think of anything except product failure, but that just seems a bit unlikely. It seems like electronics failure is the last possibility in troubleshooting.

 

[MaciekN]

Perhaps there is a severe ground loop wjen you connect it to the PC, computer psu are known for inducing lots of noise into the power lines. You could try adding a usb isolator such as adum4160 if i remember correctly, also check for loose pins on usb connector or any of the chips, perhaps some of the ground or supply voltage pins has poor contact and the signal is floating.

 

[Hi Rez]

  I just recieved an ODAC, soldered the output jack, connected it to a hedphone amp and tried A/B against my old wm8716 + cs8414 DAC. Honestly I couldn't tell much difference on my headphones, though I must admit that neither the amp (bravo audio 6n11 tube amp with 32R output impedance) or my headphones (somewhat modded Alessandro MS-1i) are top notch. Anyway I expected to be blown away, or at least that the differences would be obvious considering that ODAC should be a statement DAC when it comes to PC audio...

Unfortunate that it didn't meet your expectations.  I believe it is a decent DAC for it's price.  But IMO it would be quite a stretch to consider it a statement DAC.

 

[HaVoC-28]

  I just recieved an ODAC, soldered the output jack, connected it to a hedphone amp and tried A/B against my old wm8716 + cs8414 DAC. Honestly I couldn't tell much difference on my headphones, though I must admit that neither the amp (bravo audio 6n11 tube amp with 32R output impedance) or my headphones (somewhat modded Alessandro MS-1i) are top notch. Anyway I expected to be blown away, or at least that the differences would be obvious considering that ODAC should be a statement DAC when it comes to PC audio...

 
At level Matched all decently built DACs should sound the same , it's was i experienced comparing A-GD NFB-2/17.2 (Dual WM8741 chip), FSA Sptifire HD (PCM1798) , ODAC (ESS 9023) , Xonar DX(CS4398) and a Pioneer DVD player (PCM1754) . (Pluged to a SPL Auditor and Beyer T1 as reference can) .
 
If you don't level match them their can be some difference more or less depending on how much voltage they output .