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Hi All,
 
I'm just about to make the plunge, and have read many-many posts over many-many hours trying to decide on a headphone rig.  I've decided on the K702 and just need the final decision on the amp.  I'll be using the DAC in my Tact 2.2XP preamp.
 
I've narrowed it down to two choices:
 
Matrix M-Stage - $270 from coolfungadget
Audio-GD C2 (includes Earth op-amp) - $405 from Pacific Valve (http://www.pacificvalve.us/ADGDC2C.html)
 
I won't make use of the ACSS input on the C2, as I will feeding it directly with RCA cables from my preamp, so this might be a bit of a waste.  Is the extra cash for the C2 worth it?  The C2 seems to have a bit more rated power at 60 Ohms (1W for C2 vs. 400mW for the M-Stage); does this make any real-world difference in powering the K702 which are known to be difficult to drive?  If you had to decide between these two irrespective of price, which one would you choose and why?
 
Thanks in advance.

 

[clams]

I had my M-stage upgraded with a OPA-Moon from Audio-gd. I found that combo went really well together and helped to add some bass impact to the K702 which was pretty lacking. It definitely drives the K702 well. In fact, it is capable to driving orthodynamics like the HE-5LE so you shouldn't have to worry about that.

 

[gridlock]

Quote:

I had my M-stage upgraded with a OPA-Moon from Audio-gd. I found that combo went really well together and helped to add some bass impact to the K702 which was pretty lacking. It definitely drives the K702 well. In fact, it is capable to driving orthodynamics like the HE-5LE so you shouldn't have to worry about that.

Thanks for the info. I have already ordered an M-Stage, and will try it first with the stock op-amp.  I'll look into upgrades a bit later on.

 

[OPrwtos]

so funny! i have also "read many-many posts over many-many hours trying to decide on a headphone rig" and the funny thing is i came to the EXACT SAME CONCLUSION!! this is too much!
 
im torn between the matrix m-stage or audio gd c2.1 to go with the audio gd nfb-2 dac for the AKG K701 HEADPHONES!!
 
i really want to know what is better m-stage or c2.1 !!

 

[HaVoC-28]

Audio GD NFB-2 + M-Stage With Opa Moon + K702 =  Great Combo
 
But i am wondering if i would notice an improvement with a C2.1 or C2-SA (despite beeing discontinued it's still avaliable here in france) 
 
well c2.1 is not in stock here in France , (under 30 days ... hu ) ordering from audio gd with ACSS cable will save me about 30 € (shipping with customs , (already have to pay customs for my NFB-2 soo i know how it work ...) , 370 €
 
C2-SA is in stock  310€ with shipping   (a last shipment sent by audio GD i gess , in july it was out of stock and at my surpise , some days ago it was again in stock ) (here at the french store)
 
So going with C2-SA will save me About 50€ to 60 € , from buying a C2.1 directly from audio GD , (even more if i buy it at the french store (400 €)
 
And i have the possibility to send it back if i don't like It . (i don't want to wait a month for the amp ,) .
 
Verry hard decision , keep , the m-stage , try C2-SA (could be usefull in the futur for some very hungry cans like orthos or 600ohm beyer )
 
and sorry for my english  
 
 
 
 
 
 
 
 
 
 
 
 

 

[Mad Max]

ADA4627-1B kills OPA Moon and Earth, but if you can't solder, then AD797.

 
Quote:

Audio GD NFB-2 + M-Stage With Opa Moon + K702 =  Great Combo
 
But i am wondering if i would notice an improvement with a C2.1 or C2-SA (despite beeing discontinued it's still avaliable here in france) 
 
well c2.1 is not in stock here in France , (under 30 days ... hu ) ordering from audio gd with ACSS cable will save me about 30 € (shipping with customs , (already have to pay customs for my NFB-2 soo i know how it work ...) , 370 €
 
C2-SA is in stock  310€ with shipping   (a last shipment sent by audio GD i gess , in july it was out of stock and at my surpise , some days ago it was again in stock ) (here at the french store)
 
So going with C2-SA will save me About 50€ to 60 € , from buying a C2.1 directly from audio GD , (even more if i buy it at the french store (400 €)
 
And i have the possibility to send it back if i don't like It . (i don't want to wait a month for the amp ,) .
 
Verry hard decision , keep , the m-stage , try C2-SA (could be usefull in the futur for some very hungry cans like orthos or 600ohm beyer )
 
and sorry for my english  

You should try C2-SA since you can get it quick and return it just as quickly.  If you can post a comparison between the C2-SA and M-Stage, that would be nice.  =]

 

[HaVoC-28]

 
Quote:

ADA4627-1B kills OPA Moon and Earth, but if you can't solder, then AD797.

 

You should try C2-SA since you can get it quick and return it just as quickly.  If you can post a comparison between the C2-SA and M-Stage, that would be nice.  =]

Hum ADA4627-B series , well no soldering material here but i can manage to find some one for soldering but Opamp quest is a never ending
 
will go for C2-SA next week , waiting for some cash first ^^ (a refund  is on the way, should be completed soon )
 
And will make a comparaison between m-stage and C2-SA with my limited english . (just reading is much more easy )

 

[Kilosonic]

Quote:

I had my M-stage upgraded with a OPA-Moon from Audio-gd. I found that combo went really well together and helped to add some bass impact to the K702 which was pretty lacking. It definitely drives the K702 well. In fact, it is capable to driving orthodynamics like the HE-5LE so you shouldn't have to worry about that.

 
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It'd be awesome if someone could write more in-depth about the OPA-MOON + M-Stage (Clams? lol). Same thing for the ADA4627-1B. Haven't found too many detailed insights on either component enough for me to yet make a solid decision. But from what I've gathered so far, OPA-Moon + M-Stage + K702 has excellent synergy which is great news for me since I'm about to pull the trigger on the moon. Also heard good things about the ADA4627 but haven't found anyone directly comparing the two yet and at this point I'd prefer the moon since it doesn't require any soldering.
​

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[clams]

 
Quote:

 
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It'd be awesome if someone could write more in-depth about the OPA-MOON + M-Stage (Clams? lol). Same thing for the ADA4627-1B. Haven't found too many detailed insights on either component enough for me to yet make a solid decision. But from what I've gathered so far, OPA-Moon + M-Stage + K702 has excellent synergy which is great news for me since I'm about to pull the trigger on the moon. Also heard good things about the ADA4627 but haven't found anyone directly comparing the two yet and at this point I'd prefer the moon since it doesn't require any soldering.
​

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Caught me when I was online. I would say that the Moon is a bit too slow and dark for the m-stage, considering that the m-stage is already a slow amplifier. It's not really much of a problem except for faster paced music. It is a good match for the K702 but it made my HD650 sound absolutely horrible (bloated bass on modern recordings). In the end I settled on the OPA-SUN V2 because it played nicely with my Senns as well as still having good synergy with the K702. I found that the moon had a bit more texture on instruments but the SUN was more euphonic and fun (as well as faster) at the expense of some texture. 

 

[Mad Max]

 
Quote:

Originally Posted by Kilosonic /img/forum/go_quote.gif
 
 
It'd be awesome if someone could write more in-depth about the OPA-MOON + M-Stage (Clams? lol). Same thing for the ADA4627-1B. Haven't found too many detailed insights on either component enough for me to yet make a solid decision. But from what I've gathered so far, OPA-Moon + M-Stage + K702 has excellent synergy which is great news for me since I'm about to pull the trigger on the moon. Also heard good things about the ADA4627 but haven't found anyone directly comparing the two yet and at this point I'd prefer the moon since it doesn't require any soldering.

I originally bought Earth, Moon and Sun with my Audio-gd Compass a couple years back.  I've sold off Moon already, but I did try it briefly in the M-Stage... and I don't remember how it sounded, lol!  I noticed that it likes the M-Stage's circuit better than even the Compass circuit.  It still gets slaughtered by ADA4627-1B.  4627 nearly has no character because it is so neutral and transparent (specifically the higher B grade, the A grade is similar in sound, but warmer and not quite as mercilessly revealing).  It is textured and a bit energetic.  It makes you realize how distorted the so-called "discrete" opamps are and is much more refined in all sonic aspects.  Only AD797 can take on that opamp, really.  I have Sun put away somewhere, that's the one I enjoyed most.  For a more "musical" sound, I prefer Intersil chips, OPA209/2209, or OPA827.  OPA827 is nice with K701, but it lacks detail versus 4627 and 797.  My favorite is ISL55001 with K701, but its output DC is very bad at higher gains, so that's a no go in the M-Stage.

 

[Kilosonic]

Thanks so much you guys! Didn't expect such a quick response lol. I'm curious tho:
 
Clams - were you able to A/B the opa-moon and sun with any single/dual opamps like the ones Mad Max mentioned? Seems like I'll be making some compromises regardless of which HDAM I choose.
 
Mad Max - would you say the ADA4627-1B has the best overall synergy with the K702 of all the chips you've tried in your opinion? You noted the OPA827 lacking detail vs the 4627 but how does it compare musically? I love details but not at the expense of musicality; the 4627 would be the sure winner for me provided it's absent of any hint of "coldness/lifelessness". Also, were the 4627 class A biased? From what I read, the biasing just warms up the sonic signature slightly, is this correct?
 
hmm ADA4627-1B, guess its time to brush up on my soldering skills, or lack thereof lol.

 

[clams]

I was able to only audition it was an OPA627. I ran the OPA627 both normally and biased into class A and both of the HDAMs still had bigger soundstage and slightly more accurate imaging in my opinion. 

 

[Kilosonic]

I was able to only audition it was an OPA627. I ran the OPA627 both normally and biased into class A and both of the HDAMs still had bigger soundstage and slightly more accurate imaging in my opinion. 

Thanks Clams, i actually just found one of your older posts describing the opa-moon: http://www.head-fi.org/t/475618/matrix-m-stage-amp-review-simple-cheap-and-excellent/810

Post #822, I was very interested in your comment about its "tube-quality" sound. All the solid state amps Ive tried the k702 with either had a wee bit of harshness in the treble or a cold, analytical signature that didnt sit well with me. In any case, ive decided to get both the moon and ada4627, if the moon turns out too dark/warm to me then I'll get the sun. Im very curious to see how the 4627 will perform tho, quite a few headfiers had great things to say about the 4627 + mstage.

 

[clams]

I would say its tube-like in the fact that its extremely slow and has that smooth dark sound. However, the imitation is not as good as the real thing and I found that the bass lent from the SUN was better controlled (though less textured). 

 

[Mad Max]

 
Quote:

Thanks so much you guys! Didn't expect such a quick response lol. I'm curious tho:
 
Clams - were you able to A/B the opa-moon and sun with any single/dual opamps like the ones Mad Max mentioned? Seems like I'll be making some compromises regardless of which HDAM I choose.
 
Mad Max - would you say the ADA4627-1B has the best overall synergy with the K702 of all the chips you've tried in your opinion? You noted the OPA827 lacking detail vs the 4627 but how does it compare musically? I love details but not at the expense of musicality; the 4627 would be the sure winner for me provided it's absent of any hint of "coldness/lifelessness". Also, were the 4627 class A biased? From what I read, the biasing just warms up the sonic signature slightly, is this correct?
 
hmm ADA4627-1B, guess its time to brush up on my soldering skills, or lack thereof lol.

No coldness or lifelessness from 4627.  AD797 is strangely lifeless, and the only opamp I've heard yet to exhibit that quality.  ADA4627-1B is analytical to death, just the way I like, and a little lively.  Like I said, ADA4627-1B is very transparent, and you will listen through it far more that you will listen to it.  Musicality?  If you mean "pleasantly distorted", "discrete" opamps are the kings of that, really.  Also OPA2111AM, apparently.  OPA827 does seem a little bit more "musical" than ADA4627.  Its PRaT is a bit more, closest to LT1028 that I've heard so far.  Best bass as well.  I have not tried class-A biasing of 4627-1, only a few opamps actually benefit from that, so I pretty much never mess with class A.  ADA4627-1's soundstage is the best I've heard as well, followed closely by OPA1641, OPA827, and AD797.  Also, I wouldn't want to mess with class A as it will change the sound in a way I will probably not like.  Stock ADA4627-1B's timbre is perfect, and combined with the diamond buffers of the M-Stage, it is fully transparent to the timbre of the DAC, in my case I have a DAC19 whose timbre is perfect as well, so my rig does a pretty great job with harmonics.  Class A, even if it works with 4627, will just screw things up.