Articles, Reviews and Measurements of Audio Products (As an Amazon Associate I earn from qualifying purchases)

Review and Measurements and miniDSP 2x4 HD DSP and DAC

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This is a brief review and measurements of miniDSP 2x4 HD Processor and USB DAC. I purchased this online and seems like the price as of this writing is USD $207 as of this writing. This is a USB DAC with Toslink optical input and analog/digital in, four channel digital signal processor (DSP).

The DSP features can be used to implement everything from active speaker crossovers to full room correction/equalization. While the former functionality is easy enough to implement, the latter is up to you to program. This is a "raw" platform with no intelligence of its own. If you want room equalization, you have to figure out how to program its individual parametric filters or FIR parameters.

The unit comes in a shiny aluminum case that feels decent and has just enough weight to not get dragged too badly by the myriad of connections you would have to hang from it...

Review and Measurements of Schiit Fulla (V1) Dac and Headphone Amplifier

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This is a review and measurement of the Schiit Fulla DAC and headphone amplifier. It is the version 1 and is on kind loan from a member. If you are interested in V2/current version, I have purchased that, and the review will be forthcoming.

The Version 1 is a diminutive unit, a bit larger than the typical "thumb drive" sized USB DACs. It is made from folded metal like the larger Schiit products.
Schiit Fulla V1 DAC Picture.jpg

There are some sharp corners especially around the volume control knob that I wished were rolled off. Speaking of the volume control, it has rather low level of travel but it works and is convenient to have.

Format wise, this is an older DAC so limited to 96 kHz sampling rate as reported by Roon:

Schiit Fulla V1 DAC Roon Format Support.PNG

Yes, the USB identifier indeed says "I'm Fulla Schiit." Would be quite funny if the performance is great. Let's see if that is so in our measurements. If you are not familiar with my tests, I suggest reading my...

AES Paper Digest: Do Audio Op-amps Sound Different?

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This is a digest of the Audio Engineering Society (AES) conference paper titled, “Distortions in Audio Op-Amps and Their Effect on Listener Perception of Character and Quality.” ( As the name indicates, it is a controlled listening test to see if there is audible difference between Op-amps (integrated small amplifiers) when operated below their clipping point.

In recent years, it has become quite fashionable to talk about what Op-amp are used in audio products or swap one for the other in the same vein. While subjective outcomes abound on efficacy of such differences, question becomes if there is any formal, controlled listening tests that can give us reliable indication of audible differences in Op-amps.

The paper in question aims to answer this question. It has good pedigree when it comes to its authors which includes the famous mastering engineer, George Massenburg, and other researchers from various...

Review and Measurements of Intona USB Isolator for Audio DACs

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This is a review and measurement of Intona USB Isolator. In the last few years there has been a proliferation of USB filters, cleaners, regenerators, feeding on fear of audiophiles of noisy computer ports. Intona doesn't actually play in that market directly. They built this device for industrial control applications where strict isolation from the machine being controlled is required. Audiophiles however, have been interested in the unit just as they are in other devices in this category.

This unit is on a kind loan from a forum member. It retails for USD $229 plus $29 shipping to US. It comes in a nondescript, plastic box. No pretense of being a audio jewelry here. For this review I compared the Intona to Uptone Regen and TotalDAC D1. You can see the full collection here:

Interestingly the Intona...

Review and Measurements of RME ADI-2 DAC

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This is a review and detailed measurements of RME's new ADI-2 DAC. This is a spin off from their highly regarded ADC/DAC combo, the ADI-2 Pro. I have purchased the Pro for my testing but a member was kind enough to loan me the DAC only version reviewed here. I will measure and post any differences between the two at a later time.

The ADI-2 DAC retails for USD $999. The black version I received looks quite attractive with nice white LED highlights around controls and a high-resolution and highly responsive LCD display.

From a pure DAC functionality, it is better executed than my ADC/DAC. It has a remote control and unlike mine, has proper inputs for S/PDIF as opposed to a dongle.

The unit has huge number of settings and display material that is navigated through four switches and three rotary encoder, all of which are "clickable." Unfortunately this...

Review and Measurements of Auralic Gemini 2000 DAC and Headphone Amplifie

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This is a review and (highly) detailed measurements of the Auralic Gemini 2000 DAC and headphone amplifier. It is on kind loan from a member who has been patiently waiting for its review! :) The Gemini is a lifestyle audio device, licensing the Klutz Design CanCan and embedding a DAC and headphone amplifier in its base:

The retail price is US $1,200. Seeing how Klutz charges $550 for its base alone, this is not an outrageous sum for a unit that adds the DAC and headphone functionality and with it, remove a lot of clutter from your desk.

Looking at the slick website and the picture of the PCB, I was salivating over its design:

Auralic Gemini 2000 DAC and Heaphone Amplifier PCB.png.jpg

This is a great use of white solder mask/silk screening of the PCB. You could literally eat off of the thing! :)


Review and Measurements of LH Labs Go2Pro DAC and Headphone Amp

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This is a "naked" review and measurements of the LH Labs Go2Pro DAC and headphone amplifier. I say naked because in in the interest of time, I am posting its results by itself. I am hoping by now you all are familiar with the norms in my measurements and can see its fidelity. Actually there is one measurement that includes a comparison.

I can't find its retail price but it is on sale now with 20% off at $480 on LH Labs website. So quite pricey. The unit is on kind loan from a member.

Anyway, this is a self-powered device (although I tested it while connected via USB) and includes a 3,200 mah battery. That combined with a metal enclosure makes for one hefty device.

I find the user interface maddening. There is a simple on/off switch but then the "up" volume control is overloaded as meaning both extra gain, and filter??? I confess I could not...

Review and Measurements of Massdrop x Grace Design SDAC

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This is a review and detailed measurements and comparison of Massdrop Grace Design SDAC DAC. It is on kind loan from a forum member. The "drop" is over but when it was active, the unit costs $79. See it, and the detailed specs here:

The unit is similar size to JDS Labs OL DAC ($99 plus shipping) which I compared it to in this review:

Clearly they are after the same market and audience. While both have decent heft for what they are, they are both too light so support heavy cables and such.

The JDS OL DAC comes with an external linear power supply while the Grace SDAC is USB powered. The designer, Michael Grace, has written a nice post about the SDAC here: Reading that, seems like good engineering...

Review and Measurements of Audio-gd NFB-27.38 DAC and Headphone Amplifier

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This is a review and detailed measurements and comparison of Audio-gd NFB-27.38 DAC and headphone amplifier. It is on kind (and patient) loan from a forum member and ex-Microsoft colleague. The current website price is USD $1,688 plus shipping from China. There is no shopping cart which I assume it means you have to send money via Paypal and then wait for the unit to arrive from China. The loaned unit was purchased in China (?) and is an EU 240 unit powered by a transformer that converts 120 to 240.

The unit is massive by any definition of the word. It is the deepest piece of audio equipment I have seen let alone one for a DAC and headphone amplifier:

It can swallow four of the Topping DX7s' easily as the one on top of it right now shows. For that humongous size you get every possible input and output. I let you read all the specs for...

Hardware Teardown of Schiit Lyr Hybrid Tube Headphone Amplifier

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This is a teardown follow up to my review of Schiit Lyr Hybrid Tube Headphone Amplifier. The unit is on kind loan from a forum member.

Taking apart the Schiit Lyr, like their heavier units is a bit of a challenge as it uses an odd metal box inside another metal box. After taking out the outer box, you are greeted with the internal exoskeleton:

Schiit Lyr Headphone Amplifier Teardown.jpg

I could take this enclosure apart but that would require unscrewing the output transistors but since this unit is on loan, I chose to not do that.

Typical of most headphone amplifiers, the architecture is rather simple. To the left, covered by the box are a couple of transformers connected to AC mains (protected by a fuse). The output is rectified by a bridge rectifier and then filtered (cleaned) by the black electrolytic capacitors that are visible. They are made...

Review and Measurements of Topping D10 DAC

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This is a review of the recently released Topping D10 DAC. I purchased mine from massdrop for just $75 including shipping. I see it online from Aliexpress for $89. I must say, this is one of the most handsome budget DACs I have seen with a nice retro amber/orange 7-segment LED display:

Despite its very low price, the unit is solidly built out of thick aluminum and has good bit of heft to it. As a result, the cables connected to it stay put.

The only on the input is USB. Outputs are of course analog unbalanced RCA but also Toslink and S/PDIF coax:


Review and Measurements of SMSL M8 DAC

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This is a detailed review and measurements of SMSL M8 DAC. It is on loan from a member and seems to be have been discontinued. It retailed for $249 when it was shipping. As such, I tested it against the Topping D50 DAC which also retails for the same money.

The SMSL comes in a miniature model of high-end equipment. Shrink a high-end DAC to 1/8 scale and you get SMSL 8! That alone looks fine. The problem is they also shrunk the display by the same amount. It has extremely small fonts for that reason.

The inputs are standard for this price range and comprise of USB, optical and coax S/PDIF. Power is provided through an external switching brick (the Topping D50 is USB powered). The device was plug-and-play in Windows 10 Creators edition and I had no trouble talking to it using Roon in exclusive WASAPI interface.


Review and Measurements of Schiit Lyr Tube Headphone Amplifier

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This is a review and comparison of Schiit Lyr tube Headphone amplifier to Schiit Magni 3. The Schiit Lyr is on kind loan from a member. It is discontinued but seems to have retailed for US $450 (replaced with Schiit Lyr 2). The Schiit Magni 3 which is a solid-state headphone amplifier retails for $99 so quite a bit cheaper.

As you see above, there is quite a bit of size difference. There are after-market tube socket risers in the Lyr to make it easier to "roll" (swap) tubes. The unit came with a set of GE tubes 6BQ7A dual-triodes ( and another pair of aftermarket Russian Genalex Gold Lion E88CC / 6922 replacements ( I could not find any specs on them but they were in boxes which...

Review and Measurements of SMSL X-USB Digital Audio Converter

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This is a review and measurements of the SMSL X-USB. It is a very small form factor USB to S/SPID, Toslink optical and I2S (using mini-HDMI connector). It is on kind loan from a member.

When I say small form factor, I mean it. Here is a comparison of it to a couple of DACs I have:

SMSL X-USB Picture.jpg

Even smaller is its display as you can (barely) see in the picture. Still, I like to have that than nothing.

Heavy cables are going to drag this around but maybe with the small size you can tape it to back or top of your DAC.

Retail price that I see as of this writing is around $89 plus shipping so close to $100.

The purpose of this product is to bring USB connectivity to older DACs without such an input. Alternatively if your DAC has a poor performing USB input, you can use these devices to improve their performance assuming they also have S/PDIF input.

Let's do some measurements and see how it does. As usual, if you are not familiar with what these graphs are...

Review and Measurements of Speaka USB DAC and Headphone Amplifier

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This is a review and measurement of Speaka USB "thumb drive" DAC and comparison to AudioQuest Dragonfly Black. It is on kind loan from member Reinhold.

The Speak USB DAC is only available in Europe for a measly sum of just 10 Euros. So it would seem to be an unfair fight to compare it to AudioQuest Dragonfly Black which retails for $100 or 81 Euros although this includes Amazon Prime shipping. Either way the Dragonfly is a much more expensive DAC. So why the comparison? Because there is a rumor that the two are based on the same design.

The Speaka USB comes in a nondescript gray aluminum (?) packaging of a thumb drive with a cap. There are two LED lights on top and that is it.

Speaka USB DAC Picture.jpg

Power consumption is 70 milliamps. The Dragonfly black on the other hand draws 50 milliamps. This indicates to me that the designs are different.

Output impedance is very low at 0.7 ohm. This is at reduced volume to avoid clipping. At that threshold the Speaks...

Measurements of Oppo BDP-105 Blu-ray Player

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At our last gathering at a friend's house where we were measuring the Schiit Yggdrasil DAC, I was also asked to measure an Oppo BDP-105 player as a DAC. This player despite its age has a very positive reputation as far as fidelity. I made a complete set of measurements. I won't bore you with all of them as most were pretty good and competent until I landed on linearity test:

Oppo BDP-105 Linearity measurement.png

Yup, my jaws fell off. I repeated the measurement and still got the same. The cyan line is supposed to be the relationship between digital input and analog output. Normally it is a straight line until we get down to below -100 dB or even more. Yet here, even at the start of the test with full amplitude signal, we see clear steps in it. What it means is that the output changes proportional to input but then all of a sudden it gets stuck in a mud...

Review and Measurements of Topping D50 DAC

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This is the review and measurements of the secretive Topping D50 DAC. Other than a small picture and mention on topping's web site, there is no other information on it. I am in fortunate situation that Topping was kind enough to send me a D50 to review and keep. It was a bonus after I asked to buy the Topping DX7s. Pricing is supposed to be $249. According to Topping, it will NOT replace the D30 which makes sense as the D30 retails for half the price.

The front panel sports one of the nicest (OLED?) small displays I have seen:

Topping D50 DAC Front Panel.jpg

I like the confirmation of bit depth in addition to sample rate when playing content.

Note that this is a pure DAC. While it has volume control using a joystick to the right of the display, that only controls the RCA output. There is no headphone amplification feature in there.

Sadly my Topping DX7 remote did not work with it so to change the volume you have to be sitting close to the unit.

As you barely see, this...

Measurement and Review of Burson Play DAC & Headphone Amplifier

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This is a review and measurements of the Bursson Play DAC model "V6 Vivid." It is on loan from a member and retails for $549. It is a unique product in that it comes in form factor of a 5.25" drive bay so that you can either slide it into your desktop computer that way, or use it independently on your desk.

Burson Play DAC picture.jpg

Above you see it stacked in the middle of two Topping DACs (D50 and DX7).

The back has both ATA standard power connection for inside computer use and external 12 volt 6 amp (!) power brick.

The unit comes with a bunch of alternate op-amps that you can use to swap out what is in it. I did not play with any and tested it as I received it.

A rotary control changes the volume but requires many turns to go from min to max. Combined with rather slippery knob, made big changes difficult. But then again you get high accuracy for your level.

Speaking of level, this thing puts out some serious voltages/power. In both RCA and headphone out you get...

Measurements and Review of SMSL iDEA and AudioQuest Dragonfly Black DACs

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This is a detailed measurement and comparison of SMSL iDEA and AudioQuest Dragonfly Black DAC and headphone amplifiers. Both of these are diminutive devices in the form of "USB thumb drives." The SMSL iDEA is $86 with prime shipping from Amazon. The Dragonfly Black will cost a few more ice cream bars at $99 with prime shipping.

SMSL iDea DAC vs Audioquest Dragonfly picture.jpg

Note that connectivity is different with the SMSL iDEA having a micro USB jack whereas the Dragonfly comes with a normal USB plug.

The SMSL iDEA was kindly loaned to me from a member whereas I purchased the Dragonfly Black last fall (2017) through Amazon.

The SMSL iDEA comes in a slick aluminum package. Due to strength of material they are able to make it much thinner than the Dragonfly Black DAC. It also has volume controls which the Dragonfly lacks. Alas, every time you plug it in, it reverts to a lower volume so be mindful of that if you are doing any comparisons or measurements.

The SMSL iDEA...

Hardware Teardown of Pro-Ject Pre Box S2 Digital DAC

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This hardware teardown is a follow up to my review of the Pro-Ject Pre Box S2 DAC. The DAC performed well in objective measurements. Let's see how it does from overall design point of view.

Here is the high level diagram/major integrated circuits:

Pro-Ject Pre S2 Box Teardown pictures.jpg

We see one of the nicest layouts given the small box constraints. Digital side is fully isolated on the left with a moat between it, and the right side analog/mixed signal. The asynchronous interface is implemented using ubiquitous Xmos.

Extracted digital audio samples from USB or other inputs is then routed on top across an isolation moat and board to a pair of ESS Sabre ES9038Q2M parts. ESS is secretive with its specs so I don't have a link to provide for it or the rest of the ESS parts used here.

Precision reference voltage for the DACs is provided by ES9311...
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