Audio Science Review: Articles, Reviews and Measurements of Audio Products

Battle of Google Pixel Headphone Dongles

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This is a review and detailed measurements of three adapters to give your Pixel phone an analog output to drive headphones. Taking a lead from Apple, Google eliminated the 3.5 mm headphone jack necessitating using these external dongles/DACs+amps to use with headphones. Rumor is that Samsung may also go that way with their next phone. :(

Anyway, I received the original Google Pixel "USB-C to 3.5mm Adapter" months and months ago from a member. I was dreading having to measure it through my phone as that makes the process slow and incomplete. While I was procrastinating on that a member recently loaned me the second generation of that, prompting me to go and measure them. Fortunately I realized that using a simple USB adapter I could connect them to my PC and hence be able to measure them there. The second generation dongle retails for $12 from Google store. I don't know what the original one retailed for but I see it on Amazon for USD $14 with prime shipping.


Review and Measurements of JDS Labs EL DAC

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This is a review and detailed measurements of JDS Labs EL DAC. It retails for $249 and is kind loan from a reddit member.

The EL DAC uses the same design language/enclosure as their attractive Element DAC and Amp which I reviewed earlier. This being a DAC alone, the big knob is of course eliminated:

JDS Labs EL DAC Review and Measurement.jpg

The momentary switch enables selection of different inputs. I am afraid I could not quite get a hang of how much to push it to advance to the next setting. The color of ring around the switch indicates which input is selected which required more mental effort than this lazy brain wanted to dedicate. Then again if you just use it for USB or whatever, it is not a big deal.

The finish seems to pick some amount of smudges. Not too bad but does require more delicate care to keep it looking good long term. I see that...

Review and Measurements of WesionTEK Khadas Tone Board DAC

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This is a review and detailed measurements of Khadas Tone Board DAC from WesionTEK. It is on kind loan from the company. The retail price on Amazon is USD $99 including free shipping.

As the name indicates, this is a bare board DAC:

Kodas Tone Board DAC Review and Measurement.jpg

Don't confuse this with Raspberry Pi boards though. This is a complete DAC and doesn't need a host to operate. It is just like any other desktop DAC except that it doesn't come with a case.

The Khadas Tone Board is powered and accessed through the USB port and S/PDIF. For my review, I only tested the USB input.

Output as you see is through a pair of RCA jacks that have a great high-quality look and feel (as does the S/PDIF one). It would be at home in DACs at much higher prices.

WesionTEK sells two versions of this board, one of which mates with their host processor to make a complete networked DAC and player. They were kind enough to send me the host which I will review later.

Let's get into...

Review and Measurements of Orchard Audio Gala DAC

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This is a review and detailed measurements of the Orchard Audio Gala DAC. It is a brand new product just released and loaned to me by the company. Retail price is USD $500 but has an introductory price of $400.

The unit has unusual feature set. It has only balanced output outputs and S/PDIF digital input. And a volume control that works in digital domain. No USB input is provided but of course one can be added externally.

The enclosure looks somewhat rudimentary with blindingly bright blue LEDs that light up the ceiling of my listening room:

Orchard Audio Gala DAC Review and Measurements.jpg

Unless Orchard has done market research to know that people like Blue LEDs, my recommendation is to dim them substantially (or off).

I like the feel of the volume control. It has traditional mechanical limits which is nicer than optical encoder since you can set it to your comfortable level and have it stay there through power sequences.

The enclosure is bent/stamped sheet metal...

Review and Measurements of Micca OriGen G2 DAC & Amp

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This is a review and detailed measurements of Micca OriGen G2 DAC and headphone amplifier. It is on a kind loan from forum member. The Amazon link shows the product not being available anymore but I find it on ebay for $110 or so.

The OriGen G2 is refreshingly different from the typical DAC and headphone amp. It is an elongated metal box with nice 1/4 and 3.5 mm headphone jacks:

Micca OriGen G2 USB AUdio DAC and Preamp Review and Measurement.jpg
Nice set of LEDs indicate the sample rate. The volume control has a nice feel and its position on top makes it easier to manipulate than front mounted on small enclosures.

For inputs, we have both optical Toslink and USB, the latter of which I tested for this review.

I tested the OriGen+ version a while back and it was a nightmare to install from driver point of view. Fortunately this one is UAC2 compliant so it was plug and play with Windows 10.

Let's get into the measurements and see how she does.

As usual, I start with our...

Review and Measurements of Pi 2 Design 502DAC

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This is a review and measurements of Pi 2 Design's 502DAC. I was kindly sent by designer and forum member @Michael Kelly. It retails for 109 from his website. He was kind enough to send me a complete system with the requisite Raspberry Pi and Volumio audio operating system. As a result, the unit was turnkey in operation:

Pi 2 Design 502DAC DAC review and Measurement.jpg

I powered it up using a single supply (it allows for dual supplies). Connect an Ethernet cable or use WiFi to get a networked DAC and S/PDIF output.

In my case, since Volumio only supports 16-bit audio from my Roon player (through airplay), I resorted to playing my test files from the USB thumb drive (red and black stick). DietPi supports Roon's RAAT protocol by the way.

Support from Michael has been excellent which is always a plus in my book. He told me that the main application for this device is using it as a networked S/PDIF & AES/EBU interface (to your own DAC). The included analog...

Review and Measurements of ifi nano iDSD Black DAC and Amp

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This is a review and detailed measurement of the ifi nano iDSD Black edition portable DAC and headphone amplifier. I purchases this a few months ago from Amazon for USD $199 including shipping.

A lot of desktop and portable audio products I review are utilitarian and don't evoke much emotion. But there are some exception and the ifi nano iDSD BL is one of them. It is pretty cute!

ifi nano iDSD BL Black DAC and Headphone Amplifier review.jpg

The volume control feels nice. The metal enclosure also feels quite stout.

Included in the unit is their IEMatch resistor divider to lower noise and increase volume control range in case you need it. See my review of that functionality here:

The only input is USB. For good or bad, this is the funky iFi male USB connector which necessitates using their cable to connect to your computer. They say this makes it more...

Review and Measurements of Parasound Zdac v.2 DAC and Amp

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This is a review and detailed measurements of Parasound Zdac v.2 DAC and headphone amplifier. It is on kind loan from a member. Even though Parasound is a "high-end" audio company, this seems to be their attempt at mass market product as the retail price from Amazon is USD $523 including Prime shipping.

The unit is pretty attractive in an understated way. Please excuse the lighting as I shot this at night with my desk lamp illuminating it:

Parasound Zdac v2 DAC and Headphone Amp Dashboard Review.jpg

We have the standard optical, coax and USB inputs. But also balanced output which is nice.

Also nice is independent volume controls for headphone and line out.

Dual headphone jacks accommodating either size is very nice. Hate using adapters with headphone cords.

All in all, the Zdac makes a good impression of simplicity and nice looks.

Let's see if the measurements match the positive impression here.

As usual, we start with dashboard measurements. Here, I am showing balanced output...

Review and Measurements of ifi nano iONE DAC

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This is a review and detailed measurements of ifi nano iONE DAC. It is on kind loan from a member and it retails for USD $199 including Prime shipping from Amazon in US.

The unit is quite "cute" in a small and portable configuration (although somewhat chunky):

ifi nano iONE review.jpg

As you see from the front panel, beside the usual digital audio inputs of USB and S/PDIF coax, it also has a Bluetooth module/input. I will test that feature later. For now, my focus is on the DAC portion.

In addition to analog output, the iONE also outputs S/PDIF over the same digital input connector. It is a trademark of ifi to overload connectors this way, saving space but also creating confusion at times as to how to get the connector to act as one or the other function. As with Bluetooth, I did not test S/PDIF output for this review.

Let's get into measurements and see how she did.

As usual, I start with my Dashboard view of a full amplitude ("0...

Review and Measurements of Schiit Modi 3 DAC

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This is a review and detailed measurements of Schiit modi 3 DAC. It is a replacement for two previous products: the Modi 2 and Modi 2 Uber. I purchased the unit a few days ago for $99 plus $11.26 for shipping for a total of $110.26.

The Modi 3 DAC has the functionality of the latter with three inputs: USB, S/PDIF and Toslink which is nice. A front toggle switch (as opposed to momentary in Modi 2 Uber) selects the input. Schiit has fixed the output voltage so that it is now the full 2 volts as opposed to 1.5 in previous products. They say this is enabled by addition of an external switching power supply which you see here on top of the unit:

Schiit Modi 3 DAC Review and Measurement.jpg

For some reason I think having a black supply would go better with the black USB cord and overall gray look of the unit. Since this is a standard USB supply, I suppose you get your own version in however color or format you like.

Schiit says that this is the best measuring DAC they have...

Schiit Saga Grounding and Hum Issues?

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Readers of the forum probably remember a discovery I made regarding lack of proper grounding for safety and guarding against hum in Schiit Jotunheim. It seems that we may have a repeat of that same case with another Schiit product, the Saga preamplifier.

A forum member reached out to me regarding hum in his Saga preamplifier. He is in Europe and I don't have access to his unit so he sent me pictures of what is inside. Here is the overall shot of the inside of the unit:

Schiit Saga Hum Chassis Not Grounded.jpg

Looking at the chassis, the paint and protective coating remains which means that the top of the unit is likely not making a good connection to the rest of the chassis. As such, hum from the transformer can couple to the volume control just as it did with the Schiit Jotunheim.

Focusing on safety issues, just as well...

Review and Measurements of Fostex HP-A3 DAC and Amp

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This is a review and detailed measurements of Fostex HP-A3 DAC and headphone amplifier. Even though the product is current and listed on both Amazon and Fostex websites, I also found reviews dating back to 2011. So unless there have been some revisions, this is an "older" unit. It is on kind loan from a member and lists for USD $299 with prime shipping from Amazon.

Any memory of Fostex's long history and Japanese lineage goes out the window the moment you gaze at the ordinary and DIY-like packaging of the HP-A3:

Fostex HP-A3 Dac and Headphone Amplifier Review and Measurements.jpg

What is the deal with the huge washer on the headphone jack showing?

Functionality is not bad with USB and Toslink inputs but is missing S/PDIF. I liked seeing the RCA/Phones switch allowing me to test the RCAs as the DAC output. Note that the volume control changes the RCA levels so you can use it to drive active speakers and such, avoiding a pre-amp.

No gain switch is included which I like to see as mandatory feature...

Review and Measurements of iFi Ear Buddy (and iEMatch)

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This is a review and measurements of iFi Ear Buddy which is the cheaper, non-configurable version of iEMatch. I purchased it for USD $20 from Amazon. The purpose of both devices is to reduce the output power of a headphone amplifier. This is needed often when the headphones are too sensitive relative to the amplifier power (or volume control range), not allowing precise control of volume. In addition, many headphone amplifiers have channel imbalances at very low volumes or hiss, both of which are annoying. The idea of Ear Buddy and iEMatch is to reduce the output of the amplifier and with it, eliminate these issues.

The Ear Buddy comes in consumer packaging, hoping to embellish what is ultimately a little cable/dongle:

ifi iematch package review.jpg

Strangely, it has a pair of ear plugs in there. For a moment I thought that was their solution to reducing gain. You stick the ear plugs in your ear and then wear your headphones over that! :D

Even more strange...

Review & Measurements of Allo DigiOne Signature and DIYINHK Pro3Z

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This is a review, detailed measurements and comparison of two S/PDIF digital audio output converters. The Allo DigiOne Signature is a networked S/PDIF converter built on top of Raspberry Pi single board computer. It retails for $239. With the nice acrylic case, it goes for $259:

DIGIONE SIGNATURE PLAYER RPI SPDIF converter review and measurements.jpg

The benefit here is that you can convert any DAC with a S/PDIF digital audio input into a networked DAC. You can place your remote computer/tablet anywhere and have it stream the audio to the Allo DigiOne Signature where your audio system is. The above price does not include the Raspberry Pi which you have to add for a functional system (about $35).

My test system came with "DietPi" packaged Linux distribution for RPi which makes the unit turnkey with native support for Apple Airplay and Roon (RAAT) protocol. As such, I was able to simply power the unit and start playing files to it from my favorite audio player, Roon.

The DigiOne Signature requires two...

Review and Measurements of Oppo HE-2 SE DAC and Headphone Amp

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This is a review and detailed measurements of Oppo HE-2 SE DAC and headphone amplifier. It is on kind loan from a member. Retail price per Oppo website is $299 but I see it as used from $430 and up on Amazon. I wonder if that is because as with their Blu-ray player business, Oppo is getting out producing this device too.

The Oppo HE-2 comes in a luxurious packaging with the unit itself enshrouded in stitched leather:

Oppo HA-2 SE DAC and Portable Headphone Amplifier Review and Measurements.jpg

Intentionally or not, the look at feel of the unit seems to cater more to older clientele than the younger and typical market for headphone and DAC amplifiers.

The unit sports an ESS ES9028-Q2M so it targets high performance.

Boatload of cables and connectors come with the unit which satisfy every type of connection to every device imaginable including selection of right-angle adapters/cables.

I am sure you all are anxious to see how it measures so let's get into that.

Seeing how the HA-2 SE touts its DAC...

Rolling (replacing) Op-amps in Topping D10 DAC

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This is a study of whether changing op-amps in a DAC makes a measurable difference. Taking a lead form "rolling" tubes in tube products, a trend has started in replacing op-amps -- sometimes with much difficulty -- to improve performance of solid state products like DACs. A few months ago I tested the Topping D10 DAC and since it has a socketed op-amp, members asked if I could experiment with changing it to other pin-compatible parts. A couple of kind members supplied me with a good inventory of op-amps to test all the way up to esoteric discrete ones.

Here is the overall circuit diagram:

Topping D10 DAC PCB Board.jpg

You can see how the ESS DAC drives the OPA2134 op-amps that are soldered, providing current (I) to voltage (V) conversion. Their outputs in turn drive a pair of op-amps in the socketed Op-amp (circled) which are our output buffer/op-amps. That is the part we will be replacing.

EDIT: an earlier version of this review mentioned that we were...

Review and Measurements of Chromecast Audio Analog Performance

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This is a follow up to my review and measurements of Google Chromecast Audio's digital performance. As mentioned there, the Chromecast audio is a streaming device with integrated DAC. In the other review, I measured its Toslink digital output for usage with an external DAC. Here, I will be evaluating its analog output performance in case you want to forego the external DAC.

As noted there, the casting functionality of Chrome browser is poor and not bit-exact. So for this testing, I used Roon to play the test files and cast them to Chromecast Audio. This allows bit-perfect functionality so that we can see the performance of the hardware in best light.

The measurements are not extensive as with the digital output because my audio analyzer can't control the Chromecast Audio. But there is enough here to get a good idea of how well it does...
Review and Measurements of Chromecast Audio Digital Output
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This is a review and detailed measurements of Google Chromecast Audio digital output. The Chromecast is a tiny dongle that allows one to "cast" (stream) audio and video to a remote device. The audio version as the name implies, foregoes the video functionality and provides audio streaming. The retail cost is $35.

Chromecast Audio has dual outputs in the same 3.5 mm jack. One is the standard stereo analog. The other, by use of a cable you need to buy, is Toslink digital optical output. The appeal, and the scenario for testing in this article is that by addition of the Chromecast audio to your own DAC using Toslink you immediately turn your DAC into a networked streamer. Concern however has been raised that the Toslink output has too much jitter to be a good interconnect. In this article, I will be digging into this aspect of the device. In a future article I will measure its DAC and analog output performance.

The Chromecast Audio is a tiny round dongle. It has a USB...

Review and Measurements of Allo Boss Raspberry Pi DAC

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This is a review and measurements of the Allo Boss V 1.2 audio DAC for the popular Raspberry Pi single board computer (SBC). It was kindly sent to me by Allo. Retail price as of this writing is $65. The Raspberry Pi retails for $35 so the combination costs about $100. For that, you get a networked DAC in a tiny enclosure.

Allo is one of the few audio companies that performs real measurements of their device and the Boss was no exception. They are also quite active on forums which makes it a plus in my book as far as support and listening to customers. They have been a supporter and long time fan of ASR Forum since inception for which, I am appreciative.

The package as sent to me had both the RPI and Allo BOSS DAC in a cute acrylic enclosure, complete with "DietPi" version of Linux on micro-SD card:

Allo Boss RPI DAC Review and Measurement.jpg

Dietpi is one of a few canned versions of Linux operating system that turns the RPI into a dedicated networked/streamer DAC. It...

Review and Audio Measurement of LG G7 ThinQ Smartphone

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This is the review and measurements of the audio performance of LG G7 ThinQ smartphone. It was purchased by my son a couple of weeks ago. It retails for USD $750. Its claim to fame is inclusion of an ESS quad (four paralleled) DACs ES9218P with integrated headphone amplifier.

LG G7 ThinQ Audio Review and Measurement.png.jpg

There are actually two DACs in there with Quad DAC by default not selected.

LG G7 ThinQ Audio DAC Selection.png

I suspect they don't leave it as default because it uses more power and would hurt benchmarks and battery life.

It even has fancy audiophile reconstruction filter choices:

LG G7 ThinQ Audio DAC filter Selection.png

Default was "short" (apodizing) filter. As seen above, we did our testing using Sharp filter.

Is this all fluff or does it perform? Let's find out.

Let's start with our usual dashboard view of a 24-bit, 1 kHz tone at 44.1 kHz sampling:

LG G7 ThinQ Quad DAC Dashboard Audio Measurement.png

Wow, that is impressive. SINAD...
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