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Review: Audio-gd C2C Headphone amp vs. Little Dot MKV

post #1 of 125
Thread Starter 
Audio-gd C2C:

Little Dot MKV (Head-fi review):

MacBook Pro (24/96 output)
Van den Hul Optocoupler
Lavry DA10 (in single-ended mode most of the time)

SAEC 1903 6N RCA (A Japanese brand I'm sure hardly anyone has heard of.)
Van Den Hul The Thunderline XLR

Markl/Lawton Audio Denon D5000 ("MD5000") - 25 Ohm
Sennheiser HD650 with Zu Mobius cable - 300 Ohm, older version.
MB Quart QP55
Ultimate Ears Triple.fi 10

Everything except techno, rap and metal.
All ALAC at 44.1kHz except music from Linn Records which is 88.2 or 96.

Back when I stepped into the head-fi world, I wanted to see how far I could achieve the audio nirvana I had enjoyed at home with speakers, but without the 5-figure sum that it would require and preferably without getting too far into 4 figures. To that end, aside from with headphones, I went down the path of two devices that were "flavour of the month" on head-fi, the Zero DAC and Little Dot MKV. Through the former I gained a little education in some aspects of audio electronics, including opamps and from there, discrete opamps (HDAMs). As we discovered the HDAM and how it could transform the ZERO DAC, finding its original maker, REIZ Audio/Audio-gd, also lead me to discover its maker's line of headphone amps.

The Little Dot MKV sells for around US$300, so upon discovering that it might be possible to do better than it for around the same amount (All discrete for $330? Yes please!) I took the plunge and bought Audio-gd's C2C, as I had superseded my Zero DAC with a Lavry DA10, and the HP amp built into the Lavry was well and truly a match for the MKV.


Delivery of the C2C took longer than the MKV, but that was because Kingwa (of Audio-gd) insists on burning in and testing each unit for 100 hours before sending it to the customer. This meant about a week after payment that the unit was shipped, making almost 2 weeks before arrival for me in Japan.

Little Dot seems to have organised themselves well with packing, having a box that was designed to fit the MKV. The C2C (along with some HDAMs I'd ordered) arrived VERY well packed....in Styrofoam. Great effort, but wrong material. I grabbed a toothpick out of the cupboard to get a tiny piece of the Styrofoam out of one of the XLR sockets before hooking it up.

Whilst not up to the exacting standards of US or European manufacturers, the MKV nonetheless is a nicely assembled piece of kit. Regrettably I bought mine at the height of its popularity and there are a couple more rough edges than other people's photos seem to show. The C2C on the other hand, resembles a DIY amp in all but the circuit board. There is no nicely stenciled lettering, merely what looks like a price sticker to indicate the input selector switch and the fit and finish is a little rough, with screw holes and the volume knob asking for slightly better alignment. The volume knob on the C2C also was a cheap aluminium thing with no markings, except a dot drawn on with a marker. I immediately replaced it with a more solid $20 unit which you can see in the pictures.

Both amps are dual-mono in construction, with the MKV having individual toroidal transformers for each channel and the C2C having a single, shielded transformer in the corner. Both require that you order them with the correct voltage. The C2C is a little interesting in that solid silver wire is used for hooking up the jacks and volume pot. Otherwise, both use Alps Blue Velvet units.

First thing's first and both amps get my Denon's plugged in and the volume turned up with no music playing. A tiny amount of hiss comes from both, but, contrary to popular belief, the MKV doesn't have hum with low impedance headphones. The one time I had buzz with the MKV, it was a fault of my source. With my HD650s plugged in, with both there's just blackness.

Both amps offer dual inputs, though in the case of the C2C, the second input is balanced. While a balanced input for a single-ended output is considered pointless by some, the Lavry is a balanced DAC, I'll have to ascertain whether any benefit is gained by using it. In the case of the MKV, the two inputs are switched by pressing a button, which switches using a circuit. The C2C on the other hand, has a regular switch. In testing the MKV with two inputs connected, if a signal was being sent to one input, it could be heard, faintly, which the other was engaged. While not great, it wasn't a show-stopper for me as whatever I wasn't using as a source at any time was switched off, which I imagine would be the same for most end users.

One of the first things that is noticeable about listening to music via the MKV is that the volume knob seems to always need to be a bit higher than seems ideal. If the source is something with a proper line-out signal, it's not an issue, but in the months I've had it, I've had at least one source where I could max the MKV's volume for regular listening, and I don't listen to music seriously loud, ever. The C2C, on the other hand, is fine for listening at 9pm with my Denons and 10-11pm with my Senns where the MKV is somewhere around 12pm onwards. From 12pm things start to get painful with my Denons. In both cases, my Lavry is set to a volume level of 37 (out of 56).

Music impressions:

I'm listening to Binky's Dream from Dave McLaughlin's Extrapolation and can hear the electric guitar and saxophone notes echoing across the studio. Switching to something better recorded, The Gotan Project's Paris, Texas, the notes on the piano at the end -- you can hear the tonal changes in the strings as the notes decay. Finally I head on to Jeff Buckley and I'm lost once again in the beauty of his singing. However, through the MKV, these fine details just aren't there.

Tom Waits, with his horse voice, sometimes projected with the aid of a megaphone wouldn't have struck me as a singer that would benefit the aid of high fidelity delivery, but for all his weirdness, the C2C has brought out the beauty in what he sings more so than the MKV did.

My Denons, which go low, possibly too enthusiastically, giving everything body and impact, even when I didn't have it with other headphones, are sent by the C2C even further and with more authority into the low regions, something I had not yet encountered. Cranking up that old standard, The Crystal Method's Community Service II, the deepest bass, which through the MKV I felt needed to be tighter, is delivered with authority and control through the C2C. Three and a half minutes into Keep Hope Alive, I've now discovered a very subtle buzz to that very deep bass note, and other subtle notes played down in that region I hadn't noticed before. I have to give credit to the Lavry for the revealed detail, but for the delivery it's the C2C. I plugged my Denon's and Senns directly into the DA10 to be sure, and the bass, nor its authority just wasn't as present as much as it is through the C2C.

This prompted me to grab my old MB Quart QP55Xs, with their drivers the size of dinner plates (well, not literally) and see if the C2C could manage better at pushing their huge drivers better. The 55Xs have a much flatter and duller soundstage than my other cans, rather reminding me of mid-range AudioTechnicas but with a far better soundstage from the thicker pads. They also have a rather anemic bass and high treble. The bass can be fixed by removing a piece of felt from the foam in the back of the cups, but they are still a serious pain to drive. The result was, well, like none of these problems mattered -- treble was nice and smooth, the cymbals from Coltrane's Dear Lord coming through as, well, cymbols, the sax sweet and the bass on any heavy-duty music delivered with the same authority as with my Denons. Now nothing will save the mid-range of these cheap cans, but the C2C passed with flying colours, confirming what I'd already discovered.

If I were to attempt to describe the "sound" of the MKV, it would be that it's neutral -- it asks little and imposes nothing in return, except the natural effect of increased soundstage and separation where there was a lack of amping previously, such as with my Zero DAC or Apogee Duet. It might be as much due to the choice of opamps in the Zero -- two MC33078Ps. I experimented throwing in both LT1364s and LM4562s and the results were respectively too much of an un-emotional sound with the LT1364s and the "loudness button" effect of the LM4562s.

The C2C is another matter. After much thought, the best word to describe it would be "clear", with its transference of detail. It pushed my silver-cabled Senns into the territory of being a different headphone to what they are plugged into the MKV, my Corda Move or the Lavry. It achieves much of what I wanted of an amp, something that would take a top source and deliver it with exacting detail across the spectrum, without falter, but let me down, coloring the sound in a detrimental way with some of my headphones.

At one point, while moving equipment around, I thought I'd both have another listen with my Apogee Duet as the source, as well as experiment with interconnects. The C2C revealed that, indeed, the Duet wasn't quite up there with the Lavry, lacking that last bit of detail and musicality. A lesser pair of ICs was the same, again, the last bit of detail wasn't there. Finally, switching the Lavry to balanced mode and hooking in an XLR pair of Van Den Hul's The Thunderline (you have to admit that's an awesome name for an interconnect) the result was quite clearly a slightly smoother sound, something VDH cables have a reputation for in all but their top models.

But what if....?

As one of my primary reasons for buying the C2C was it being all discrete, an idea occurred to me: How much of the difference between the amps was opamp vs. discrete? What if I were to put two HDAMs in the MKV? Could Audio-gd's very own HDAM modules upgrade the MKV to match the C2C's performance? Opening it up, I found just enough space to fit two HDAMs with extension wires, so into it two of Audio-gd's Earth modules went.

Van Halen's Year to the Day, which I selected for the guitar intro was my first test. The buzz from the guitar amp, clearly spatially separate in the C2C, sounding like it were sitting away and to the right, was less distinct through the MKV, more as if it were a buzz in the recording or equipment than from Eddie's amp. The sound of the piano at the end of The Gotan Project's Paris, Texas was still lovely, but that last detail of the decaying tones in the strings that the Lavry extracts wasn't there in the MKV. Having not listened to it through better equipment, I was pleasantly surprised when I switched to the C2C to hear the changing tones of the strings as the notes decayed. Jeff Buckley, Hiromi, Sara K, Coltrane and others told the same story, that the lovely separation, space and details instruments and voices have through the C2C just isn't quite there in the MKV, even with HDAMs, and less so stock. It rather reminded me of the differences between the DA10 and my Apogee Duet, or between a good set of interconnects and one of the cheap sets I plugged into test the difference -- the detail just isn't there. The C2C's "I'm going to grab your bass and everything else by the balls and show you what it's made of down to the last hair" just isn't there either.

Sticking two HDAMs into the MKV certainly makes for an improvement to it, but the MKV feels as if it just doesn't have the power to drive headphones to their best regardless, either low or high impedance.


So where do I begin? The Little Dot MKV has been a staple of Head-fi since Penchum's review, being a good design and good value for $300. With the C2C, with its hand-made case, I feel I must be like those people who built themselves a DIY amp to exceed what could be achieved by a better commercial amp for far less money, except that I didn't build the amp myself. I'm using a DAC that's 3x its price as my source and I'm glad I am! Most of all, I'm thoroughly enjoying all my music over again, the DA10 and C2C revealing that last detail I've been searching for throughout the entire sound spectrum. If anything the C2C is too good and I should be comparing Audio-gd's cheaper SS amps with the MKV, for if the C2C exceeds the MKV so well, then I wouldn't be surprised if their cheaper amps will match or better the MKV, even with a HDAM upgrade!) for less money.

After I wrote up most of this review, I took my gear around to LobsterSan's office for a 2-person mini-meet so we could try out headphones we'd never heard before. Afterwards I thought some more about the C2C's performance with various headphones. I realised that where the C2C seems to shine is with low impedance cans and seriously wished that I had a pair of AKGs handy, as this could be the perfect bargain solid-state amp to bring them out of their shell considering how it brought out my Denons. As well, it would be interesting to try Grados and Ultrasones with them for the same reason. I did, however have a pair of Ultimate Ears Triple.fi 10s handy -- and yes, I think I'm onto something, as the result with them was a sound that was much fuller than what I was used to out of my Corda Move. (Edit: I realise now, after writing this, that solid state amps generally do better with low impedance cans, while tube amps do better with higher impedance headphones though it's not universal. I guess I re-discovered the wheel here.)

Though it's a $330 Chinese hand-made HP amp, it has quite a bit of interesting technology in it, and, IMO is good value. The Little Dot MKV is a decent amp, better than, say, the HP amp built into the Zero DAC or Apogee Duet, and most notably, very neutral in its presentation, but exceeded in other ways by Audio-gd's C2C, for around the same money.


Thanks for reading my first full review on Head-fi.
post #2 of 125
Thread Starter 

Quick notes

  • The amp comes good -- very and noticeably good in fact at the 350 hour mark (or thereabouts, I wasn't counting), just as Kingwa suggested. It seems this time is needed for the transistors to full burn in.
  • I've switched back to using my Japanese SAEC copper cables as opposed to the slightly tamer (albiet with better soundstage) Van Den Hul The First Ultimate as Northstar DAC I'm now using has a very tame sound already.
  • The headphone socket is a Chinese rip-off of a Neutrix one. I had to bend the internal contacts a bit to stop the music dropping out sometimes. I'm going to suggest to Kingwa that he use proper sockets in the future.
  • You can use XLR-RCA adaptors with the RCA inputs with no problem.

December 17:
  • My Ultrasone Edition 9s arrived and ....yes, just yes.
  • I've changed my one-word description from "silver" to "transparent" as switching between the Lavry and the Northstar DAC, I was clearly hearing the difference between both DACs.
  • Whereas the MKV would give the effect of the singers being in a bigger studio compared to listening directly from a Duet or Zero, the C2C does this, but also boosting the bass and treble.

January 15:
Kingwa has informed me that the C2C will no longer come in a hand made box and will be tuned to a more neutral EQ in the future.

February 8:
The C2C now comes in a manufactured, instead of hand-made box. This is a huge improvement over the hand-made case. It also comes with a proper Neutrik headphone jack.

post #3 of 125
Your review reflects my own experience w/the audio-gd gear. Neutral, dynamic, utterly transparent, while remaining engagingly musical. It's rare that anything lets you "hear into" the recording quite as much while still leaning in the fun/musical side of things, never in the analytical/dry side. You should give the DAC8 a try, astonishing.
post #4 of 125
Great first full review, Currawong! Can't wait for internal pics of this thing.
post #5 of 125
Thanks for the review, now I feel like trying it with the JVC dx1000 to get a taste of how they sound with a SS amp.

With your Denon and HD650, do you prefer the sound with the balanced internconnects? Do you think it is worth it to get XLR cables for this amp ?
post #6 of 125
I've heard several times how the K701 REALLY shines with a good SS amp.
post #7 of 125


Wonderful review
Love the impressions, I also look forward to the internal images
post #8 of 125
Oh, if anyone is interested in my in depth review of the Reiz/Audio-GD dac, preamp, and amp, see here:

Review: Audio-GD C1 Amp, C3 Preamp, and DAC8 D/A Converter

And let me qualify this - I believe Reiz/Audio-gd is a major player as far as sound quality and engineering go. I'm talking krell/levinson/pass labs territory here. I don't pass out praise very often, but in this case it is richly deserved.

Addenum - this gear also takes a looong time to fully break in. I've had a lot of high end gear pass through my system and this has taken by far the longest to reach potential. 400 hours, minimum, before you can really get a full flavor of it, and that's in addition to the 100 hours that they put on it at the factory.
post #9 of 125
Originally Posted by Tyson View Post
Oh, if anyone is interested in my in depth review of the Reiz/Audio-GD dac, preamp, and amp, see here:
That is some serious audio, thanks for the review and congrats with your purchases
post #10 of 125
thanks for the review.

with shipping included the c2c is around $400?
post #11 of 125
Thread Starter 
Tyson, I'm glad I'm not the only one who's impressed. I put off posting this review for a while because while I've listened with a lot of high-end audio, I haven't enough with high-end head-fi. However, what it did for the Lavry told me I wasn't hearing things. As well, since reviews of the Burson buffer explained what what was going on, giving me more confidence in my review.

shotmaker: That's a tough question, as the XLR cables I have are a different brand to the RCAs I have and it's not trivial to switch with the Lavry. On Monday LobsterSan and I are having our second micro-meet and I'll experiment with his Benchmark DAC1 which has both types. I don't think there would be a huge benefit though, but honestly I don't have enough experience to say for certain. I'm more practical in that the C2C is convenient if you want an amp that has the option for both types of input.

Originally Posted by glitch39 View Post
I've heard several times how the K701 REALLY shines with a good SS amp.
This is one of those moments I regret selling the ALO K701s you see in the second picture.

An interesting thing is, Kingwa sent me the web pages of the C2, the big brother to the C2C, which while single-ended also, can be built (I imagine) for balanced headphones. It's much the same design as the rest of his hi-fi, but for headphones, and <$700. I'm seriously tempted!
post #12 of 125
Wow, looks like a serious piece of amp.

Head-fi always keeps me thinking... I really want to give this amp a shot, haha.
post #13 of 125
Great job on the review CW.....as you know I'm a audio-gd fan as well (DAC8/CD7 here I come, next year). I've eagerly awaited your report as it were on the C-2C and have to say thanks for a throughly impressive first piece of work...

Kudos for taking your time to get to know the amp very well before posting a review on it !

Major thumbs up !!!

post #14 of 125
good review. Thanks!!
post #15 of 125
Thread Starter 
Thanks PP.

An update on the XLR vs. RCA question: I had a chat with an audio guru friend about XLR connections. XLR is used in pro audio to avoid ground loop issues, as it connects the ground of the components together. When this question came up, what immediately came to mind were the HDAM opamp experiments a few of us did with the Zero DAC, where the ground wire of the HDAM was attached in various places. Attached to the (combined) signal return of the RCA jacks, the PRAT improved, as if the Zero suddenly had a better power circuit. Again, I don't know enough about electronics to be sure, but the ground on the HDAM is a different thing to the ground in XLR cables. Unless components are specifically designed to gain some kind of signal improvement through using the ground wire of an XLR interconnect (aside from solving ground loop issues), using an XLR connection wont yield any benefit and may actually degrade the signal according to my friend. There might, I imagine, be a benefit in a particular device if the RCA jacks use a common signal return and the XLR not. Someone who actually knows audio electronics properly feel free to clarify any of this.
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