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How good could be a very small dac/amp unit ?
This is a quite convenient dac/amp,  , because it has the size of an usb key , and you can move it easily from one computer to an other.  It's a relatively recent product, and I  saw a head-fi moderator using it with a "high end" headphone.


It's the AudioQuest DragonFly Asynchronous USB DAC.

Hence my question, how good could be something that small ?
In comparison my xonar stx soundcard , is much more bulky, not portable, and not as expensive.

  • saratoga
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How good could be a very small dac/amp unit ?
Reply #1
Sure. High quality single chip amp sac and USB devices exist. I would not assume that is one of them without some testing results though.

  • stephan_g
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How good could be a very small dac/amp unit ?
Reply #2
Uses some ESS DAC (my money would be on the ES9023) and a Wavelength Audio based USB interface solution. Seemingly substantial headphone driving abilities within the limits of USB supply. Could be pretty good if designed well. Sure it's small, but look at what they cram into mobile phones nowadays, and with what kind of part sizes. Or what's inside an ordinary Clip+.

You'd mainly need the USB interface, the DAC and a headphone driver or beefy opamp. A 4-layer PCB or thereabouts for a compact layout wouldn't hurt, I guess.

Sure the STX is much bigger. It can afford to be, and takes advantage of it. You wouldn't be expecting relays, film caps and socketed DIP-8 opamps in a micro-sized affair (even if some of that is of dubious benefit). Besides, it uses TOTL (consumer) converters, which require more external circuitry to begin with, and it has like 2 stereo DACs and one ADC, IIRC. Having some decently high supply voltages means you are not restricted to RRIO opamps either. Performance standards are a little different, too.
  • Last Edit: 11 June, 2012, 05:24:12 AM by stephan_g
My little "blogalike":
http://stephan.win31.de/music.htm

How good could be a very small dac/amp unit ?
Reply #3
Uses some ESS DAC (my money would be on the ES9023) and a Wavelength Audio based USB interface solution. Seemingly substantial headphone driving abilities within the limits of USB supply. Could be pretty good if designed well. Sure it's small, but look at what they cram into mobile phones nowadays, and with what kind of part sizes. Or what's inside an ordinary Clip+.

You'd mainly need the USB interface, the DAC and a headphone driver or beefy opamp. A 4-layer PCB or thereabouts for a compact layout wouldn't hurt, I guess.

Sure the STX is much bigger. It can afford to be, and takes advantage of it. You wouldn't be expecting relays, film caps and socketed DIP-8 opamps in a micro-sized affair (even if some of that is of dubious benefit). Besides, it uses TOTL (consumer) converters, which require more external circuitry to begin with, and it has like 2 stereo DACs and one ADC, IIRC. Having some decently high supply voltages means you are not restricted to RRIO opamps either. Performance standards are a little different, too.


So this dragonfly dac/amp could compare more to a sansa clip+ , rather than a xonar stx ? 
It would be nice if I could find measurements for this dragonfly dac/amp (snr, thd, etc...)  , I guess this would help to get  a better idea.
Otherwise audioquest does not hesitate to sell 500$ cable, so at the end, I won't be surprised that this small  dac/amp  is just overpriced.
  • Last Edit: 11 June, 2012, 09:28:27 AM by extrabigmehdi

  • LithosZA
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How good could be a very small dac/amp unit ?
Reply #4
I don't trust AudioQuest based on all those expensive HDMI/Power cables they sell.
Maybe the quality is the same as something like this?
http://www.bhphotovideo.com/c/product/6755...e_Amigo_II.html
or
http://www.tigerdirect.com/applications/se...C7BBTkwCjCECjCE
Who knows?

  • saratoga
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How good could be a very small dac/amp unit ?
Reply #5
Since their specs are a little vague, and no one has tested it, I'd probably pass.  For that kind of money I'd expect them to provide some actual details about how well it performs.

  • mzil
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How good could be a very small dac/amp unit ?
Reply #6
I don't trust AudioQuest based on all those expensive HDMI/Power cables they sell.
Maybe the quality is the same as something like this?
http://www.bhphotovideo.com/c/product/6755...e_Amigo_II.html
or
http://www.tigerdirect.com/applications/se...C7BBTkwCjCECjCE
Who knows?


Agreed. There's no doubt in my mind that  such products (at least some) are indistinguishably just as good, yet a fraction of the price. [I personally use a slightly larger Behringer UCA202 for my notebook, which adds RCA ins and outs, Toslink, and a volume pot for the headphone jack. Using such USB corded or dongle devices also puts less torque strain on my notebook's delicate USB jacks, too, so I avoid using these plug in box designs, whenever possible.]

Also, I make it a point to not support companies I believe to be snake oil peddlers, as much as possible, even if they happen to have a particular product in their line that seems reasonable, and I encourage others to act similarly.
  • Last Edit: 11 June, 2012, 12:19:12 PM by mzil

How good could be a very small dac/amp unit ?
Reply #7
Also, I make it a point to not support companies I believe to be snake oil peddlers, as much as possible,


I'd like to, but seems harder and harder. You have some reputable brand like sennheiser, that release a 2000$ solid state amp, or a 800$ iem able to reproduce frequency range of 5 to 46,000Hhz . Even the highly praised hd800  have some dubious marketing (headband that absorb vibrations ...    ).
  • Last Edit: 11 June, 2012, 12:25:53 PM by extrabigmehdi

  • mixminus1
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How good could be a very small dac/amp unit ?
Reply #8
I don't trust AudioQuest based on all those expensive HDMI/Power cables they sell.
Maybe the quality is the same as something like this?
http://www.bhphotovideo.com/c/product/6755...e_Amigo_II.html
or
http://www.tigerdirect.com/applications/se...C7BBTkwCjCECjCE
Who knows?

The Amigo II is a big "maybe", but the Creative X-Fi is actually pretty good, although it has a somewhat high output impedance for driving headphones (~8 ohms) - see NwAvGuy's measurements of the Turtle Beach Micro II (not sure how closely it's related to the Amigo II - appearance and price are very similar) and the Creative X-Fi.

The Behringer 202 is surprisingly good, as well, although the very high output impedance of its headphone jack (47 ohms) will result in less-than-neutral performance with most headphones under 250 ohms or so.
"Not sure what the question is, but the answer is probably no."

  • saratoga
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How good could be a very small dac/amp unit ?
Reply #9
Or just get a fiio E7.  Its about 100 bucks, and will drive just about everything.

Of course its larger, but I prefer that. I've badly bent the USB headers on a system before with one of those USB key DACs by knocking the headphone with my elbow while they were connected to the system.  Now I don't trust that style at all.

How good could be a very small dac/amp unit ?
Reply #10
Or just get a fiio E7.  Its about 100 bucks, and will drive just about everything.

Of course its larger, but I prefer that. I've badly bent the USB headers on a system before with one of those USB key DACs by knocking the headphone with my elbow while they were connected to the system.  Now I don't trust that style at all.


I favor using a short cable with a  USB A male connector and a USB A female connector on it to mechanically decouple the USB appliance from the body of the PC or laptop

  • AndyH-ha
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How good could be a very small dac/amp unit ?
Reply #11
Just a note, and question (if any answer exists) about the USB cable option. I have a couple of cables plugged into USB ports from the boxes under the desk, with the ends setting close at hand on top of the desk. Flash drives, which I use often, work fine but two out of three mp3 players, a card reader, and a USB hard drive will not. Those have to be plugged directly into a port; they just will not work through an extension cable.

The mp3 players draws some power from the USB connection, so possibly that is relevant, although I would not think it should make a difference. The hard drive has its own power supply, so that surely isn't a factor. The flash memory card reader should use about the came amount of current as the flash drives. Anyone else experience something similar?

  • saratoga
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How good could be a very small dac/amp unit ?
Reply #12
Just a note, and question (if any answer exists) about the USB cable option. I have a couple of cables plugged into USB ports from the boxes under the desk, with the ends setting close at hand on top of the desk. Flash drives, which I use often, work fine but two out of three mp3 players, a card reader, and a USB hard drive will not. Those have to be plugged directly into a port; they just will not work through an extension cable.

The mp3 players draws some power from the USB connection, so possibly that is relevant, although I would not think it should make a difference. The hard drive has its own power supply, so that surely isn't a factor. The flash memory card reader should use about the came amount of current as the flash drives. Anyone else experience something similar?


I don't think extension cables are even allowed by the spec, so probably they're just perturbed by the extra cable enough to give up trying to talk to the host.

  • pdq
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How good could be a very small dac/amp unit ?
Reply #13
There is also such a thing as an active USB extender cable. They are typically 5 meters long, and have essentially no signal loss, so should work fine with external hard drives etc.

How good could be a very small dac/amp unit ?
Reply #14
Just a note, and question (if any answer exists) about the USB cable option. I have a couple of cables plugged into USB ports from the boxes under the desk, with the ends setting close at hand on top of the desk. Flash drives, which I use often, work fine but two out of three mp3 players, a card reader, and a USB hard drive will not. Those have to be plugged directly into a port; they just will not work through an extension cable.

The mp3 players draws some power from the USB connection, so possibly that is relevant, although I would not think it should make a difference. The hard drive has its own power supply, so that surely isn't a factor. The flash memory card reader should use about the came amount of current as the flash drives. Anyone else experience something similar?


I don't think extension cables are even allowed by the spec, so probably they're just perturbed by the extra cable enough to give up trying to talk to the host.


You are making this up, right?

A USB extension cable is just that - an extension of a USB cable. Experience shows that shorter cables can be plugged together up to the usual 5 meter limit for passive USB-2 cables. I've used them for hard drives and DVD drives.
  • Last Edit: 11 June, 2012, 05:35:34 PM by Arnold B. Krueger

How good could be a very small dac/amp unit ?
Reply #15
I don't think extension cables are even allowed by the spec, so probably they're just perturbed by the extra cable enough to give up trying to talk to the host.

As I have recently read, there is no such thing as extension cables for USB 3.0 SuperSpeed devices.
That said, I've never had any problems with extension cables and High-Speed USB 2.0 devices. Passive Hubs and long passive cables could provoke problems, but with <= 2m extension cables I'd not expect any. At least as long devices have passed the logo test.

  • saratoga
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How good could be a very small dac/amp unit ?
Reply #16
You are making this up, right?


Why would you accuse of me of lying?

A USB extension cable is just that - an extension of a USB cable. Experience shows that shorter cables can be plugged together up to the usual 5 meter limit for passive USB-2 cables. I've used them for hard drives and DVD drives.


Alright, well if you're no they're in the spec, just link the page number.  No need to be rude about it.

How good could be a very small dac/amp unit ?
Reply #17
USB 2.0 spec, p92:
Quote
6.4.4  Prohibited Cable Assemblies
[...]
Prohibited cable assemblies may work in some situations, but they cannot be guaranteed to work in all
instances.
•  Extension cable assembly
A cable assembly that provides a Series “A” plug with a series “A” receptacle or a Series “B” plug
with a Series “B” receptacle.  This allows multiple cable segments to be connected together,
possibly exceeding the maximum permissible cable length.
[...]


How good could be a very small dac/amp unit ?
Reply #18
USB 2.0 spec, p92:
Quote
6.4.4  Prohibited Cable Assemblies
[...]
Prohibited cable assemblies may work in some situations, but they cannot be guaranteed to work in all
instances.
•  Extension cable assembly
A cable assembly that provides a Series “A” plug with a series “A” receptacle or a Series “B” plug
with a Series “B” receptacle.  This allows multiple cable segments to be connected together,
possibly exceeding the maximum permissible cable length.
[...]



Adultery is still against the law in many states and municipalities. Following the logic apparent above, the  presence of these laws means that since adultery is against some law that is written down some place, adultery never actually results any sex acts being satisfactorily completed. ;-)

If you believe that or what's written above...

How good could be a very small dac/amp unit ?
Reply #19
You are making this up, right?


Why would you accuse of me of lying?


I guess you don't know what lying actually entails. I'll leave the etymology lesson for your own personal studies and edification. ;-)

I spoke for myself - I am incredulous that someone thinks that USB extension cables don't work and pose a serious threat to the operation of real world systems.

Are you accusing me of lying when I said that I've used them zillions of times and if simple rules are followed - they just work? ;-)

A USB extension cable is just that - an extension of a USB cable. Experience shows that shorter cables can be plugged together up to the usual 5 meter limit for passive USB-2 cables. I've used them for hard drives and DVD drives.


Alright, well if you're no they're in the spec, just link the page number.  No need to be rude about it.


You appear to be demanding a proof of a negative hypothesis. ;-)

But it doesn't matter because even if there was some rule that appeared to be construable into a true statement that extension cables are usually or even just often seriously detrimental to the operation of high speed USB systems, there is always the matter of what really works.  Note that I only spoke of what works for me (and by logical extension a goodly number of other folks).

How good could be a very small dac/amp unit ?
Reply #20
Recently there was some hype regarding this AudioQuest DragonFly at head-fi . The moderator jude posted a review raving this dac, so off course lot of people want it.
The most intriguing part of review:
Quote
here's what the Dragonfly also is: It is a USB bus-powered DAC that is built around an ESS Sabre DAC chip (audiophile-approved buzzword item, check); has asynchronous USB transfer via Gordon Rankin's Streamlength code (big-time audiophile-approved buzzword item, check); 64-step analog volume control (check); support for up to 24/96, including 24/88 (check); and is the size of a USB thumb drive


So yeah after reading that review you are tempted to believe it's something exceptional and convenient for only 250$.
http://www.head-fi.org/t/617241/audioquest...ng-tiny-dac-amp

  • saratoga
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How good could be a very small dac/amp unit ?
Reply #21
I guess you don't know what lying actually entails. I'll leave the etymology lesson for your own personal studies and edification. ;-)


Are USB cables really so important to you that petty insults and appeals to etymology are preferable to just answering an honest question or admitting I wasn't "making this up"? 

But it doesn't matter because even if there was some rule that appeared to be construable into a true statement that extension cables are usually or even just often seriously detrimental to the operation of high speed USB systems, there is always the matter of what really works.


In this case, the problem was that the extension cable did not work, so your premise is false.  My point is that because the standard disallows it on the ground that it may not work, its not really the device's fault if it doesn't work.  Things that are nonstandard do not have to work.  They usually do work, but extension cables also degrade signal quality quite a bit in my experience, and its perfectly allowable for standards compliant devices to simply refuse to talk to them.

Recently there was some hype regarding this AudioQuest DragonFly at head-fi . The moderator jude posted a review raving this dac, so off course lot of people want it.
The most intriguing part of review:
Quote
here's what the Dragonfly also is: It is a USB bus-powered DAC that is built around an ESS Sabre DAC chip (audiophile-approved buzzword item, check); has asynchronous USB transfer via Gordon Rankin's Streamlength code (big-time audiophile-approved buzzword item, check); 64-step analog volume control (check); support for up to 24/96, including 24/88 (check); and is the size of a USB thumb drive


So yeah after reading that review you are tempted to believe it's something exceptional and convenient for only 250$.
http://www.head-fi.org/t/617241/audioquest...ng-tiny-dac-amp


I wouldn't put much faith in someone's subjective evaluation of a DAC based on a few pairs of relatively easy to drive, high impedance headphones.  Its not much of a test of the amplifier, and even if it were you have little idea how your preferences will compare to his.  I think my point above still stands:  before spending any real money on a DAC, its a good idea to see actual specs if not 3rd party testing.  If there are no meaningful specs, its probably better to just buy something you know will work well rather then take a gamble on something that may or may not.