Articles, Reviews and Measurements of Audio Products

Review and Measurements of Schiit Sys Passive Pre-amp/Switcher

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This is a measurement and review of the Schiit Sys switcher and passive pre-amp. It retails for just $49 plus shipping which is reasonable. The unit is on loan from a member so not new.

Schiit Sys 20180208_145701.jpg
I will do a teardown later but for now, there are just two inputs, one output, and a volume control in there. No other passive or active components.

Let's start with frequency response at different volume control settings:

Schiit Sys passive volume frequency response measurement.png

Frequency response is essentially rule flat to 30 Khz which is nice.

Channel matching starts with a small deviation and grows to 0.5 db at 12:00 o'clock volume setting. Lowering the volume to 3:00 o'clock increases this error to 1.3 dB. So probably not a good idea to use it below 12:00 position.

Phase measurement between channels is boring and inconsequential:

Schiit Sys Phase Shift Measurement.png

Let's look at channel separation:

Schiit Sys Channel Separation Measurement.png

Bottom two lines are...

Soekris DAM1021 R2R DAC Measurements

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I have finally managed to borrow a Soekris R2R sign magnitude dac to measure. Essentially I bought this dac for a speaker project. I was/am agnostic about the DAC technology, however there is no denying R2R measures more poorly than typical delta sigma. I was particularly interested in its FPGA filtering capabilities for crossover duties. Ultimately it wasnt the solution I wanted so the dac now resides with a friend who has put it in a box with very pleasant subjective results.

Note that I had a few issues with 50Hz and harmonics pick up. I will investigate later, so crap below 1kHz please ignore. I have measured this DAC under other circumstances previously and I know its not an issue with it.

This board is the 0.05% resistor version which will exhibit higher harmonic distortion (maybe 9dB or so) than the more expensive 0.01%/0.02% resistor version

The unit is driven I2S over HDMI cable from a Gustard U12...

Measurement and Review of Schiit BiFrost Multibit DAC

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This is a review and measurements of Schiit BiFrost Multibit DAC. It retails for $599 plus shipping and is on loan to me from a kind member of the forum. For this review I will be comparing it to the Topping DX7 which retails for $200 less ($399).

Note that this is the special "multi-bit" version of the BiFrost DAC which uses a R2R ladder DAC from analog devices (AD5547). This is an extra cost option.

The Schiit BiFrost Multi-bit comes in a plain looking silver box. It is more substantial than the smaller DACs they offer like the Modi 2 but it still does not give one feeling of high-end or high-quality.


Connectivity is very sparse with USB, Coax and Toslink inputs and only unbalanced RCA output. No AES/EBU digital input or balanced outputs. In contrast the Topping DX7 has all of these other inputs/outputs in addition to headphone output.


A cheezy toggle switch in the back turns the...

Teardown of the Emotiva DC-1 DAC

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This is a teardown of the Emotiva DC-1 DAC and headphone amplifier as a follow up to my review of that unit (see

Here is an overall shot of the unit:

Emotiva DC-1 DAC and Headphone Amp PCB inside 20180202_132513.jpg

Overall layout is good. AC mains comes in from the right, goes up to the transformer. Below that we have the digital cluster and flow is to the left ending in analog and headphone outputs.

Immediately though, there is a major source of concern. Check out the IEC plug:

Emotiva DC-1 Missing Ground Lug 20180202_132521.jpg

We have a 3-prong, grounded IEC socket but the ground lug doesn't go anywhere! It must be connected to the case as this is metal and an electrical short can energize it. Only a double insulated piece of equipment can be run on two wires. Which this is not.

This is a major safety flaw! I can't recommend purchasing this equipment on this basis!

And look at how the mains hot...

Measurement and Review of Emotiva DC-1 DAC

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This is a detailed measurements and review of Emotiva DC-1 DAC. It is kindly loaned to me by member Sal1950. It retails for $499 including shipping from Emotiva direct. The features and size is very close to my recently reviewed Topping DX7 DAC.

As you see in above picture it has extensive set of inputs and outputs. We get USB, Coax and Toslink S/PDIF, and balanced AES/EBU digital input. But we also get an analog input! On the output side we have both balanced and unbalanced. It includes a built-in power supply with a toroidal transformer which I appreciate at this price point.....

Topping DX7 DAC & Headphone Amplifier Review and Measurements

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This is a detailed review and measurements of the Topping DX7 DAC and integrated headphone amplifier. Frequent readers of this forum know that I am a fan of Topping D30 DAC. It measures excellently and is a bargain at $130 shipped. While the D30 has distinctly budget feel to it, such is not the case with Topping DX7. From cardboard packaging and custom foam to the heavy aluminum case the DX7 brings a much higher quality feel. It nearly rivals my Exasound E32 at 15 times the price. I purchased mine through Amazon for $299 shipped. Strangely it shows not available anymore:


Front panel as is an OLED display which has great contrast and gives nice confidence of what is being played as far as sample rates and formats (DSD and...

Measurement and Review of JDS Labs USB OL DAC

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This is a measurement and comparison of JDS Labs USB OL DAC against the NWAVGUY's Objective DAC (also sold by JDS Labs). I also compared it to my reference budget DAC, the Topping D30. See my measurements of Objective Rev b DAC here:

And topping D30:

The JDS Labs OL DAC comes with USB-input variant at $99 which is what I purchased. And another with Toslink optical input pushing the price a whopping $40 more to $139. The Objective DAC sells for $129 which is the same price as Topping D30. But topping is a lot more feature rich with Toslink and S/PDIF inputs.

As you see in the above picture, the OL DAC improves on the Objective...

Hardware Teardown of Topping D30 DAC

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This is a hardware teardown and analysis of Topping D30 USB DAC. No doubt many of you have read my review of the D30 and know that it is my current favorite for a budget DAC ($129). There seems to be two revisions of this DAC out there so this will outline the unit I tested.

Four hex screws releases the back panel allowing the board to easily slide out without much adventure:

Topping D30 USB DAC Top Board Teardown.jpg

The board is clean with no modifications, soldering issues or any problems visible. No, you don't want to "eat of it" but for a value-oriented product, I see nothing wrong with it. Here is the revision of the board by the way:

Topping D30 USB DAC Revision.png

This larger than normal budget DAC board sizes affords very good separation between the digital and analog side. Connectors are nicely spaced out which should reduce crosstalk. On top of that, there is a nice...

Review and Measurements of iFi iPurifier S/PDIF Digital Audio Filter

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This is a detailed measurement and review of iFi iPurifier. This is a device that is advertised to clean up your coax S/PDIF signal from all ills including the common flu to audio distortions. It is a tiny little box the size of a thumb drive:

Not shown is the fact that it actually needs external power and iFi ships it with their switching wall-wart "iPower" power supply.

This is not a filter device but rather, one that receives digital data over S/PDIF, buffers it (puts it in memory) and then retransmits it. iFi has a nice block diagram of it on their site:


Who wouldn't want their waveform cleaned up in red and turn it into the one in cyan? It is like getting an enema. Not that I have had one but I imagine it being the same.

Because the iPurifier regenerates S/PDIF, it should have good ability to remove...

Review and Measurements of Gustard U12 USB to S/PDIF Converter

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This is a review of Gustard U12 which converts USB input to S/PDIF, Toslink, AES/EBU and I^2S. The U12 retails for $170 shipped from Amazon as of this writing. I will be comparing it to Audiophilleo 1 (about $500), Fiio E10K ($76) and Melodious-Audio MX-U8 ($269). Sadly my Berkeley Alpha USB is broken so I can't test against it even though it is at much higher price point.

Gustard U12.jpg
The Gustard U12 is for people who have existing DACs and would like to add USB connectivity to it. The device has very good functionality with both consumer S/PDIF and AES/EBU...

Measurement and Review of Hifime Sabre 9018 USB DAC

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Time for measurement and review of another budget DAC: the Hifime Sabre 9018 USB audio DAC. It retails for $80 shipped from Amazon. The closest device I have to it is the Fiiio E10K USB audio DAC which costs nearly the same at $76 on Amazon. Click to see the detailed review of Fiio E10K.

The Hifime comes in one of the lowest budget packages I have of any DAC. It is a tiny, plastic unit with permanently attached 3-4 inch USB cable and a 3.5mm headphone jack. It has a sole red LED light indicating it is on. Even the plastic package it came...

Electrical Grounding Talk

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No doubt you all are familiar with audiophiles attempting to make their systems better with dedicated grounding systems for their audio equipment. Incredible amount of myth and wrong intuition is involved in such motivations and endevour, sometimes leading to very unsafe electrical systems that are not compliant with electrical safety code.

I was online and got prompted by youtube to watch this video by Mike Holt. Not sure how many of you know him but his is the most famous electrician I know. He has had an online community for seemingly forever and they argue almost as much as we do about audio! Anyway, here he is giving a talk I think for other electricians on what grounding is, and is not. Because it is a trade talk, it may be a bit challenging at times to follow but it is still a very well done presentation. He goes over key principles that are gotten wrong by audiophiles and electricians alike. And walks through the scenarios where dangerous conditions are created.


Hardware teardown of FX-AUDIO DAC-X6 USB DAC

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This is a hardware review of FX-AUDIO DAC-X6 USB DAC. For measurement and listening tests go to this article:

As noted in that review, this is an ultra low cost $58 DAC and headphone amplifier. They provide the overall block diagram thusly:


And that matches what is inside:


I have indicated with arrows the flow of signals. Following the USB input, we go into Via VT1603 USB interface. The digital data is then handed to Crystal Semiconductor CS8416 which is also the S/PDIF interface. The provides the serial interface to the heart of this device, the Cirrus Logic CS4399 DAC which costs about $6 in volume. The analog output then gets buffered through Ti/Burr Brown OPA2134. From there, this path splits. One goes to the rear RCA jacks and the other, to TI6120...

Measurement and Review of FX-Audio DAC-X6 DAC (compared to Topping D30 and Fiio E10K)

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This is a (very) detailed measurements of FX-Audio DAC-X6 audio DAC and headphone amplifier. It also includes my listening impressions as usual. The FX-Audio DAC-X6 retails for just $58 shipped from Amazon:


Comparisons will be made against Fiio E10K which retails for $78 and Topping D30 DAC ($120). See my review and comparison of those products here: For the second part of this review, I also include the comparison to Exasound E32 DAC ($3,400 retail):

When I was close to finishing the review, I was under the impression that this was a $120 DAC or more. Imagine my...

Hardware Teardown of Schiit Modi 2 USB DAC

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A recent discussion in the review of Schiit Modi 2 reminded me that I was planning to do a hardware teardown of it. As reminder, the Schiit Modi 2 is a low cost ($120 shipped) USB DAC.


Audio is captured through the USB port and output on those pair of RCA jacks. The only thing unusual is that "E/S" switch that puts the DAC either in 24/96 mode or supports higher resolution to 192 KHz (different USB classes). It is an ill-intended feature especially since Windows 10 Creator Edition no longer requires drivers for either mode.

The unit is simply designed but uses a very hefty gauge of formed sheet metal which gives the unit nice weight to sit on the desk unlike many budget dacs, Screws are threaded which is nice and easily open and expose what is inside. The silver color is utilitarian and is not going to...

Master Index for Audio Hardware Reviews

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This is a thread to make it easier to find reviews and measurements of DACs, players, audio tweaks, etc. It is in reverse chronological order (newest first). I will update as I do more reviews.

Review and Measurements of JDSLabs ODAC Rev. B Compared to Fiio E10K

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This is a concurrent review of two DACs, the famous "O2 DAC" by Nwavguy from our neck of the woods and the E10K Olympus 2 from Fiio. They both use the TI PCM5102 DAC chip so makes for an interesting comparison.

Retail price for the JDSLabs version of the O2 DAC is $149 through Amazon:


The Fiio E10k Olympus 2 is half the price at $73:

Fiio E10K.jpg

While the ODAC is quite sparse package with just a USB connector and 3.5mm output, the Fiio E10 has a headphone amplifier with both bass boost and gain settings, plus a S/PDIF coax output. They are both quite small and fit in your hand so are great portable solutions to take on the road if needed.

Construction quality on...

JJ's Signal Processing and Psychoacoustics Master Library

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We are privileged to have James Johnston ("JJ") as one of our members. As one of the luminaries in audio research, it has been a pleasure to read his past presentations to the local chapter of Audio Engineering Society. JJ has kindly given me permission to post links to his work per below. I suggest downloading them and reading them before bed. :)


Octave files
lplt_t3.m Octave program (jan 2014 & feb 2015)

Heyser Lecture
From the 133rd AES Convention, October 2012, San Francisco. 1.2MB PPTx deck.

Hearing & Psychoacoustics
Soundfields vs. Human Hearing Download (900k ppt)
Hearing Tutorial (131st AES, NYC, 2011)...

Review and Measurements of Shozy Alien+ Digital Audio Player (DAP)

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This is a highly detailed review and measurements of the "audiophile" digital audio player, Alien+ by a company called Shozy out of Singapore. These players use "desktop" class DAC silicon and such, aiming to produce the same sound you would get from your home system. They also have much higher power headphone output than say, a cell phone.

The Shozy Alien+ is an all metal portable player. That makes it quite hefty but also pain in the hands to use because of super sharp corners. As is, I don't think I could use this device without some kind of skin/case.

Here is what they say about it and a picture of the unit:


Much to my surprise, the unit would not power on without putting a micro-SD card in there! Nor could I find a manual for it anywhere online. The unit was loaned to me and fortunately the person who had bought it told me about having to put the microSD card in there.

Even worse is that while the Alien+ is powered using a...

Budget DAC Review and Measurements: Behringer UCA222

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UCA222 is an extremely low cost DAC/ADC targeted at home recording consumers. For this review I measure its DAC and headphone output performance. This is an ultra low cost device retailing at just $30 with shipping included! As such, it is an "Amazon Choice" product:


The device is obviously made out of plastic but it is not as cheesy as that sounds. The metal red color makes it look like it is made out of metal. The UCB cord as you see is permanently attached so no tweaking with $1000 UCB cables is possible! :D

Functionality is pretty good given the headphone output, optical S/PDIF and aforementioned analog to digital converter. Unfortunately sampling rate is limited to 48 Khz.

For this testing I did my comparison against two other low cost DACs: the Topping D30 ($129) and...
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