[UntilThen]

HD650 powered by o2+odac was how I started off with head-fi. It was thoroughly enjoyable for 2 months until I bought a tube amp, the Darkvoice 336se. Still using the o2+odac as dac, the Darkvoice gave the hd650 a warm and lushness that makes you want to listen to music for hours. This is the magic of tubes. Once you've tasted it's goodness there's no turning back. 

 

[bracko]

  Would I need to use high gain if I get a pair of 400i's?

I use my HE-400i on 1x gain. I have 1x/3x on my amp. It works great.

 

[MrMateoHead]

  I actually ordered the O2 Amp+ODAC yesterday after some replies to my same question on the HD 650 thread.  Regarding the current PC setup - I don't have a dedicated soundcard, just an MSI Z87M Gaming motherboard.  I didn't get it because of the headphone amp but it is listed as a feature.  Obviously all amps are not created equal but I didn't realize how true that would be!  I'll post my thoughts on the O2 after it arrives later this week.

Your board is really nice. Your headphone amp is the TI OPA1652. It is rated 2 mA per channel, so at 1 V that is approximately 4 mWs total. That is actually quite a lot of power, but won't hold a candle to the O2 unless the chip is getting much better voltage (I couldn't find detailed info). Supposedly, the HD650s need about 0.13mWs to reach 90 dB, so your board could probably do it with a little headroom (but the dynamic range of the stuff you listen to will still matter). In any case my guess would be that you have a great sound card, but not really a powerhouse of a headphone amp (though I'd love to try it out myself).
 
Feed an O2 the line out and you will be loving it - just shut off all the ancillary soundblaster junk. I hated the "crystallizer."

 

[thejammonster]

 
Your board is really nice. Your headphone amp is the TI OPA1652. It is rated 2 mA per channel, so at 1 V that is approximately 4 mWs total. That is actually quite a lot of power, but won't hold a candle to the O2 unless the chip is getting much better voltage (I couldn't find detailed info). Supposedly, the HD650s need about 0.13mWs to reach 90 dB, so your board could probably do it with a little headroom (but the dynamic range of the stuff you listen to will still matter). In any case my guess would be that you have a great sound card, but not really a powerhouse of a headphone amp (though I'd love to try it out myself).
 
Feed an O2 the line out and you will be loving it - just shut off all the ancillary soundblaster junk. I hated the "crystallizer."

 
Interesting info.  I've got a new motherboard on the way (new PC build) - MSI Z170A Gaming M9 ACK.  They make excellent boards and I've built my last 3 PCs with them.  Here is the info I can find from the product page:
 
3x headphone amp (type not listed, possibly a similar TI chip?)
ESS SABRE ES9018K2M DAC
C-Media 6632A audio codec chip (32-bit/384kHz)
Chemi-Con caps
Nahimic Sound Technology (I think this is a Sound Blaster equivalent)
 
I'm not sure if the detailed info you found is out there yet as this board was just officially released today, but if you can find it I would love to know.  My O2 is still on the way and I don't plan on this motherboard replacing it but it is pretty cool to see the push for high-end audio.  On-board audio used to be a joke compared to a dedicated sound card!

 

[HotIce]

Your board is really nice. Your headphone amp is the TI OPA1652. It is rated 2 mA per channel, so at 1 V that is approximately 4 mWs total. That is actually quite a lot of power, but won't hold a candle to the O2 unless the chip is getting much better voltage (I couldn't find detailed info). Supposedly, the HD650s need about 0.13mWs to reach 90 dB, so your board could probably do it with a little headroom (but the dynamic range of the stuff you listen to will still matter). In any case my guess would be that you have a great sound card, but not really a powerhouse of a headphone amp (though I'd love to try it out myself).
 
Feed an O2 the line out and you will be loving it - just shut off all the ancillary soundblaster junk. I hated the "crystallizer."

 

The 2mA is the rated quiescent (opamp consumption with no load) current. Sustained max is about 30mA.

 

[MrMateoHead]

   
Interesting info.  I've got a new motherboard on the way (new PC build) - MSI Z170A Gaming M9 ACK.  They make excellent boards and I've built my last 3 PCs with them.  Here is the info I can find from the product page:
 
3x headphone amp (type not listed, possibly a similar TI chip?)
ESS SABRE ES9018K2M DAC
C-Media 6632A audio codec chip (32-bit/384kHz)
Chemi-Con caps
Nahimic Sound Technology (I think this is a Sound Blaster equivalent)
 
I'm not sure if the detailed info you found is out there yet as this board was just officially released today, but if you can find it I would love to know.  My O2 is still on the way and I don't plan on this motherboard replacing it but it is pretty cool to see the push for high-end audio.  On-board audio used to be a joke compared to a dedicated sound card!

That board is actually a beast - I love MSI's stuff. I've never seen an ESS DAC used in a motherboard also - that is quite amazing. The headphone amp looks to be the same TI 1652 - but with 3 of them included, that provides either 6 channels of amplification, or maybe just 1 running in series or parallel?. Unclear. Without knowing what sort of voltage they are getting, I can't guess at the power it will produce. All the parts are great parts, but we don't really know how they perform because we don't know how well they are implemented.
 
I seem to recall, but could not find, that the TI chips usually have 10 Ohm output impedance, which is their worst aspect - they are going to work best with headphones rated from 80 ohms on up (and new headphones are coming out daily in the 30 ohm range). It would need to produce over 100 mWs to best the O2, and 100 mWs would already be orders of magnitude more than the HD 650 requires.
 
But I have little doubt that the soundcard section should provide high quality, if not better quality, than a lot of people's AV receivers / Headphone DACs. For this board, assuming it was low-noise ("hiss free") - I would assume you might want only a better amp.
 
I also did just learn that a lot of Pre-Amp stages in AV receivers use similar parts all the way up to the $3,000 mark, yet they all do not measure the same, that is for sure. We all need good parts, AND good design. Wish I was an electrical engineer!

 

[MrMateoHead]

 

 
Your board is really nice. Your headphone amp is the TI OPA1652. It is rated 2 mA per channel, so at 1 V that is approximately 4 mWs total. That is actually quite a lot of power, but won't hold a candle to the O2 unless the chip is getting much better voltage (I couldn't find detailed info). Supposedly, the HD650s need about 0.13mWs to reach 90 dB, so your board could probably do it with a little headroom (but the dynamic range of the stuff you listen to will still matter). In any case my guess would be that you have a great sound card, but not really a powerhouse of a headphone amp (though I'd love to try it out myself).
 
Feed an O2 the line out and you will be loving it - just shut off all the ancillary soundblaster junk. I hated the "crystallizer."

 

The 2mA is the rated quiescent (opamp consumption with no load) current. Sustained max is about 30mA.

Thank you for the correction - so would that be 30 mA total, or 30 mA per channel? I would think per channel. Do you know what the typical, actual power output might be on a mother board? For some reason I assumed the supply voltage wouldn't be greater than 12V, and more likely +- 5 V

 

[thejammonster]

 
Thank you for the correction - so would that be 30 mA total, or 30 mA per channel? I would think per channel. Do you know what the typical, actual power output might be on a mother board? For some reason I assumed the supply voltage wouldn't be greater than 12V, and more likely +- 5 V

 
MSI's website seems to indicate 5V.

 

[thejammonster]

  But I have little doubt that the soundcard section should provide high quality, if not better quality, than a lot of people's AV receivers / Headphone DACs. For this board, assuming it was low-noise ("hiss free") - I would assume you might want only a better amp.

 
I ordered the JDS Labs O2 Amp+ODAC and had a rear dedicated 3.5mm line-out added since it was only $3.  Am I correct that this should bypass the ODAC and have the O2 acting as only an amp and my motherboard as the DAC?  If so, best $3 I've spent in a while!

 

[Takeanidea]

If it's anything like my Epiphany it will; I don't even plug my o2/odac into the mains I just plug my headphone amp in

 

[Bibo]

   
I ordered the JDS Labs O2 Amp+ODAC and had a rear dedicated 3.5mm line-out added since it was only $3.  Am I correct that this should bypass the ODAC and have the O2 acting as only an amp and my motherboard as the DAC?  If so, best $3 I've spent in a while!

Overriding the ODAC and using only the O2 is always possible via the front 3,5mm port. on additional rear output you can connect another amp and use only the ODAC

 

[thejammonster]

  Overriding the ODAC and using only the O2 is always possible via the front 3,5mm port. on additional rear output you can connect another amp and use only the ODAC

 
Thanks, I had it backwards.  After re-reading the website I had confused input/output.
 
"The front, right 3.5mm jack on O2+ODAC provides shared functionality: analog input to the amplifier, and paralleled ODAC line output."
 
'analog input to the amplifier' is the key here.

 

[Bibo]

With the additional port you can use in and output simutanously. The $3 are still a good investment, espcially if you plan to use powered desktop speakers like I do.

 

[HotIce]

Thank you for the correction - so would that be 30 mA total, or 30 mA per channel? I would think per channel. Do you know what the typical, actual power output might be on a mother board? For some reason I assumed the supply voltage wouldn't be greater than 12V, and more likely +- 5 V

 
It's 30mA per opamp (per channel, at least - configurations like the O2 has parallel opamps per channel, which would double the max current throughput).
Hard to say if HP amp rails runs at 12v or 5v. The former is what I would use, but not sure they did.

 

[MrMateoHead]

 

 
Thank you for the correction - so would that be 30 mA total, or 30 mA per channel? I would think per channel. Do you know what the typical, actual power output might be on a mother board? For some reason I assumed the supply voltage wouldn't be greater than 12V, and more likely +- 5 V

 
It's 30mA per opamp (per channel, at least - configurations like the O2 has parallel opamps per channel, which would double the max current throughput).
Hard to say if HP amp rails runs at 12v or 5v. The former is what I would use, but not sure they did.

So assuming a 5 V max power, we have a range of maybe 2 mWs to 150 mWs per channel though at an unknown impedance (output as well an input).