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

Review and Measurements of Audeze Deckard DAC and Amp

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This is a review and detailed measurements of Audeze Deckard DAC and headphone amplifier. It is on kind loan from a member and seems to be discontinued. Seems to be a product of year 2016 with retail price of USD $699. Owner has bought it used for much less.

The unit has rather unusual hefty metal enclosure with super sharp extruded aluminum edges that can easily pierce your fingers:

Audeze Deckard Headphone Amplifier and DAC Review.jpg

Other than that, the volume control feels very nice. There are RCA outputs and inputs in the back. The RCA out is variable and seems to just be connected to the output of the headphone amplifier. I only tested the unit as a DAC+Amp combo. With the front toggle switch, seems like you can use it as just a headphone amp/pre-amp if you wanted.

Looking for information on it, I ran into a CNET review saying this:

1544216992924.png


Is Steve Guttenberg right? Let's find out!

Measurements
I adjusted the output to typical 2 volt...

Review: Apple vs Google USB-C Headphone Adapters

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This is a review, detailed measurements and comparison of Apple's USB-C adapter to the current and last version of Google Pixel headphone adapters. The Apple adapter costs just $9 including one day shipping for free. The Google dongle costs $12.

Not that any of these are large by any stretch but Apple's is also the smallest of the three:

Apple iPhone USB-C Headphone Adapter Audio Review.jpg

Oddly there is no apple logo or markings on the device. The others don't have it either but I thought Apple would insist on that.

All three adapters work in Windows with the appropriate adapter and that is how I tested them, allowing my analyzer to fully control and quantify their performance.

Format wise, Apple's supports the key ones:
Apple iPhone USB-C Headphone Adapter Audio Formats Supported.png


So very similar to Google Pixel V2 and better than V1 which only supported 48 kHz.

Note that volume control in Windows is active at all times even if you use WASAPI exclusive mode!

Not much else to talk about than getting into...

Study: Headphone Amp Gains: Low or High?

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This is an analysis of whether you are better off using low or high gain mode in a headphone amplifier in their overlapped region. Traditional rule of electronic design says there is no free lunch: higher gain means higher noise. While this has become the "conventional wisdom" and one that I routinely state myself, forum member asked if there is any hard data to back this. So I decided to test the theory on two headphone amplifiers: the Schiit Magni 3 and JDS Labs Atom.
Schiit Magni 3 Headphone Amp versus JDS Labs Atom Gain Review.jpg

The test matrix here is infinite in scope. What volume does one choose for each gain to test? After pondering for a second or two :), I decided to go the defensible route of setting low gain to max and then matching the same in high gain. Both of these amplifiers have analog volume controls and in high gain, they can be touchy as far as getting accurate levels out of them but I managed to get close enough.

Let's see what the measurements say.

Measurements...

Review: Battle of Schiit Audio DACs

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This is a review, detailed measurement and comparison of Schiit's Modi 2 (uber), Modi 2 Multibit and Modi 3. I have reviewed the Modi 2 uber and Modi 3 before so this is mostly focused on how the Modi Multibit compares to them. I have purchased all of them personally at different times. The Modi 2 Uber is now replaced by Modi 3 with the latter costing USD $99 plus shipping. The Schiit Multibit fetches quite a premium compared to that to the tune of USD $249 plus shipping. Is the extra cost worth it? This is what this review is about.

Starting from the top, Schiit seems to be playing with its design in each one of these units:

Schiit Modi Multibit Review Compared to Modi 3.jpg


Switch type, color and finish seem to vary some...

Review and Measurements of Audirect Beam and AQ Dragonfly

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This is a review, measurement, and detailed comparison of two "thumb drive" sized combo DAC and headphone amplifiers: the Audirect Beam and Audioquest Dragonfly Black. I had reviewed the latter last year but it was with my old measurement gear so I thought I perform a fresh set of data on it given the popularity of Dragonfly. I purchased the Audirect Beam from Amazon a few months ago for USD $104 (about $114 with tax). I purchased the AQ Dragonfly for USD $99 from Amazon just the same. The Audirect Beam is on sale for $80 on massdrop and hence the reason I thought I review it now just in case you want to take advantage of its sale.

The Audirect Beam is the smallest DAC+amp I have seen, sans the phone USB-C dongles:

Audirect Beam Portable DAC Review.jpg

It has a spring-loaded, nice feeling momentary rocker switch for turning the volume up or down. Sadly in practice it would not change level correctly, requiring multiple toggles.

The volume control changed the...

SMSL SU-8 Version 2 Balanced DAC

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This is an update to my previous review of SMSL SU-8. At a retail price of USD $212 on Amazon and balanced outputs, the SU-8 could provide a very compelling proposition. Unfortunately the performance of the balanced output in my first review sample was disappointing, showing significant switching noise. SMSL was kind enough to send me a second unit recently and I put it to test.

There is no functionality difference so see the previous review for details of that. Briefly here, you get a nice looking unit with a tiny display and remote control:
SMSL SU-8 DAC Version 2 Review.jpg

[the 44.1 kHz on the display is not showing all the way due to my camera shutter not being in sync with its refresh rate.]

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

Measurements
Let's start with our unbalanced dashboard:
SMSL SU-8 DAC Version 2 Unbalanced Measurement.png


This...

Preview: Monolith by Monoprice Desktop THX Headphone Amp & DAC

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This is an early look of the Monolith by Monoprice Desktop Headphone Amplifier and DAC with THX amplification technology. The unit was kindly purchased by a forum member and drop shipped to me. And that is where the trouble began but more on that later. The Monoprice THX amp and DAC retails for USD $480.

The Monoprice THX amp and DAC has the same design language of other "monolith" units which translates to a serious look. There is brushed metal on front and very shiny and glossy enclosure which instantly shows fingerprints:

Monoprice Monolith Desktop Headphone Amplifier and DAC Review.jpg


Let's backtrack a bit. I have ordered three products from monoprice. The first one never came and I only found out about it a few months later. I then ordered two other products from them both of which were sent to a remote neighbor. Their street and house number are one digit off from us. Hard to imagine how someone could be this bad at reading addresses yet be in delivery business.

Worried that this unit would also...

Review and Measurements of Allo DigiOne RPI S/PDIF

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This is a review and detailed measurements of the Allo DigiOne Raspberry Pi digital audio (S/PDIF) interface. It retails for USD $99 and is on kind loan from Allo. Unlike its higher-end brother (DigiOne Signature), this is a single board implementation at half the price.
Allo Digione Raspberry Pi SPDIF Output Jitter Review.jpg

When combined with a Raspberry Pi, and a suitable "audio operating system" (e.g. Volumio used in this review), you have a $135 networked S/PDIF interface. Hook the output of this board to your favorite DAC and you automatically add networking to it, allowing you to place the computer server elsewhere and stream content to your audio system.

Testing digital audio outputs is quite different than our typical analog measurements. Here, we are interested in how pure the digital output is as to produce good performance out of any DAC regardless of how good its S/PDIF interface is. I took a shot at this when...

Tear down of Neurochrome HP-1 High Perf Headphone Amp

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This is a tear down of the Neurochrome HP-1 High performance Headphone amplifier. My review of HP-1 showed exemplary distortion and high power handling. With kind permission from its designer, here is a look at what is inside.

Here is a lower resolution shot of the PC board:

Neurochrome HP-1 Teardown PCB low res.jpg


For 4X higher resolution, click on this attachment:

Neurochrome HP-1 Teardown PCB med res.jpg

You may have seen my tear down of massdrop THX AAA 789 amplifier which had plenty of empty space. Not so here. As you see, nearly every inch of space is used.

Unlike the massdrop THX 789, the power supplies for the HP-1 are internal. We have two switching supplies from the reputable Mean Well Taiwanese company. I am assuming one...

Review and Measurements of Apogee Groove DAC and Amp

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This is a review and measurements of the Apogee Groove portable DAC and headphone amplifier. It is on kind loan from a forum member. As small portable DAC+Amps go, its retail price of $295 is quite high. I see factory refurbished ones at $149 though on Apogee website.

Apogee is best known for their professional audio products so their entry into personal audio is quite a departure for them.

As USB audio "thumb drive" form factors go, the Apogee is quite a bit more substantial:

Apogee Groove Portable DAC and Headphone Amplifier review.jpg


Volume wise, it is probably double the size of typical thumb drives. The larger size allows rubberized up/down volume buttons with excellent feel. There is no "plastic" feel to the unit either, making you think you can sit on it and nothing bad would happen to it.

The three LEDs roughly show the volume level. During music playback, they change to color to green and are fully analog. Each has individual intensity which once maxed out, lights up the one above it...

Tear down of Massdrop THX AAA 789 Headphone Amp

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With kind permission of the owner, I took apart the Massdrop THX AAA 789 headphone amplifier. If you have not seen it yet, check my my review of Massdrop THX 789.

The internal structure of this unit follows other models from Massdrop. I was impressed with the effort to keep all the components on one side using mostly SMT (surface mount) parts. The bottom of the PCB is only through-hole pins which I am assuming was wave soldered.

Here is lower resolution shot of the PCB with my annotations:

Massdrop THX AAA 789 teardown main PCB reduced2.jpg


Click on this attachment to get 4X higher resolution image.

Massdrop THX AAA 789 teardown main PCB reduced.jpg

I have 4X larger image yet again. Send me a message if you want that.

The biggest shock here is that there is no "THX module" of any sort! No custom or hybrid parts that I can see. Instead, we have a bunch of exclusively Texas Instruments parts...

Review and Measurements of Neurochrome HP-1 High-Performance Amp

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This is a review, detailed measurements and comparison of Neurochrome HP-1 high performance headphone amplifier to Massdrop THX AAA 789. It is on kind loan from company designer and owner, Tom Christiansen. I learned about Tom in chasing a review he had done of a passive volume control. I was very impressed with his depth of knowledge and thorough analysis using an Audio Precision analyzer. Tom is an analog designer, having worked for famous and large leaders in the industry (National Semiconductor and Texas Instrument). He is quite active in DIY audio forum, sharing his knowledge of engineering and audio. Needless to say, I was excited to get my hands on his products to test starting with his HP-1 headphone amplifier given its superlative measured specifications.

The HP-1 comes in all forms from bare PCB to fully populated board and finished package. I received the latter:

Neurochrome HP-1 Headphone Amplifier Review.jpg

The retail price for this version is $1,249. Bare...

Review and Measurements of Nobsound NS-DAC3 Pro DAC & Amp

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This is a review and measurements of Nobsound NS-DAC3 Pro DAC and headphone amplifier. It is on kind loan from a member. I see it on Amazon for USD $140 with free shipping from China.

This is the type of DAC you see in tons of Chinese websites with tempting features for the price. As you can imagine, there is nothing glamorous about such products. The packaging is as cheap as you can get. There is even a small CD with the drivers for your nostalgic feelings about computing days long gone. A couple of photocopied pages complete the picture as far as the manual is concerned.

The metal enclosure is not bad though and brings some uniqueness in this super crowded market:

Nobsound NS-DAC3 Pro DAC and Headphone Amplifier Review.jpg


As you can see, increasingly we see Bluetooth added to these small DACs. Also nice is dual headphone jacks.

In the back we have the usual S/PDIF, Toslink and USB inputs.

Anyway, let's see how she measures.

Measurements
Here is the dashboard view using the headphone jack...

Inside ifi iOne Nano Portable DAC and Headphone Amplifier

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I reviewed the ifi nano iOne a while back. Before sending it back and with owner's permission, here are the guts of the unit.

I don't have much time to do a reverse engineering on it. So I will provide the top and bottom images of the PCB and let you all do that if interested :).

Here is the bottom side of the unit: (click on the image for full size)

ifi ione nano DAC teardown top PCB.jpg


I have marked the main engine: the DSD1793 DAC.

Clearly visible at the bottom is the all-in-one module from CSR for Bluetooth.

I can't see the markings for U500 on the right. And the numbers for the tiny output buffers seem proprietary to iFi.

Assembly looks very clean with no manual re-work.

Here is the top side:
ifi ione nano DAC teardown bottom PCB.jpg


The main item is the XMOS USB interface on a daughter card. Nice to see glue on the connectors to keep it from coming lose.

I also...

Review and Measurements of New JDS Labs Atom Headphone Amp

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This is a review and detailed measurements of JDS Labs Atom Headphone Amplifier. It was kindly sent on loan by JDS Labs in advance of its formal announcement and availability this week. It retails for USD $99. As such, I will be comparing its performance to other $99 amplifiers such as Schiit Magni 3 and Monoprice Liquid Spark.

The Atom is a nice departure from the JDS O2 in having proper RCA connectors in the back and 1/4 headphone jack in front (and 3.5mm in the back):

JDS Labs Atom Headphone Amplifier Review.jpg


The enclosure is plastic and lightweight but is stable enough to not move around with the weight of cables.

As you see in the comparison above, it is about 10% wider and deeper than O2. The volume control feels slightly less good than the O2 with the latter having more of a "hydraulic" feel.

There is not much else to say about it so let's get into the measurements and see how she does.

Measurements
I started my measurements with a dashboard view of unity gain with 2...

Review and Measurements of Monoprice Liquid Spark Headphone Amp

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This is a review, detailed measurements and comparison of Monoprice Liquid Spark, Schiit Magni 3 and JDS Labs O2 headphone amplifiers. The Liquid Spark and Magni 3 retail for $99 but only the Monoprice comes with free expedited shipping. The JDS Labs O2 retails for USD $139 on US Amazon with free Prime shipping. JDS sells it direct for $129 plus shipping. So roughly speaking, all three are in similar price range.

The three headphone amplifiers look very different from each other:

Monoprice Liquid Spark Headphone Amplifier review.jpg

As you see, the liquid spark is quite chunky compared the other two. It also generates a bit of heat although nothing remotely of concern.

Connectivity is funky on the JDS O2 with 3.5 mm headphone jack for input. The other two have proper RCA inputs in the back and 1/4 inch in the front.

The Liquid spark comes with a large laptop style external switching supply. The other two have heavy linear wall-wart supplies with the Schiit Magni 3 being quite a...

Ethan Winer Builds a Wire Null Tester

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Ethan has built a null tester for testing audio interconnects to reveal differences between them. He has a new video on it which is kind of long on intro but then gets to the meat of the argument toward the last third:

Review and Measurements of Monoprice Portable Amp and DAC with THX

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This is a review and detailed measurements of Monoprice Portable Headphone amplifier and DAC with "THX AAA" technology. I purchased this earlier in the week for USD $279.99. With tax it came to little over $300.

For those of you who don't know, THX has come up with amplification module with feed forward error correction which serves to lower distortion in amplifiers. My review of Massdrop THX Headphone Amplifier showed it to have exceptional performance, far and above anything I have measured before. So excitement has been built up for the same technology (but not identical part) used in Monoprice version. Here, we are treated to a portable headphone amplifier and DAC all in one.

The Monoprice Monolith THX has a very serious, business-line appearance:

Monoprice Monolith THX Portable DAC and Headphone Amp Reviews.jpg


It is similar to a modern smartphone but much thicker and...

Review and Measurements of Audio-gd NFB28.28 DAC and Headphone Amp

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This is a review and detailed measurements of Audio-gd NFB-28.28 DAC, headphone amplifier and pre-amplifier. It is on a kind loan from a member and retails for USD $750 plus shipping from China. The unit is quite heavy so I suspect shipping will cost a few dollars.

This is a deep enclosure but half the width of the larger Audio-gd products:

Audio-gd NFB28.28 DAC and Headphone Amplifier Review.jpg

Navigating the unit is maddening. 7-segment LED digits are used to indicate input number, setting, etc. I searched for the manual but could not find any. Instead there is some random text on Audio-gd website that starts to deal with something about a problem they fixed. How a simple device is made so complicated is beyond me. The unit could stand serious cleaning up of the documentation and revamping of the user interface.

There are lots and lots of inputs and outputs. I let you read the documentation for yourself. For my testing I used the USB input and either balanced XLR output for DAC...

Review and Measurements of Chord Mojo DAC and Amp

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This is a review and detailed measurements of Chord Mojo portable DAC and headphone amplifier. It is on a kind loan from a member. Retail price is USD $599 but I see Amazon showing it for $532 including prime shipping.

The Mojo is a small but chunky and heavy as portable headphone amplifiers go:

Chord Mojo DAC and Headphone Amplifier Review.jpg


The case feels like it is filled with lead and you could run a car on top of it and have it escape unscathed.

Let me get out of the way that I am not a fan of its whimsical look. But much worse is forcing a human to decode hues and color intensity of lights to detect what mode the unit is in. Why oh why? For $600, I expect something more informative than what is offered here. I will for example happily take a rotary volume control over those two blue buttons for volume level.

The Chord products are popularized by its designer, Rob Watts who is quite active online, and in audio shows/conferences. Having technical designers mingle with social media...
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