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

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 listing ASR’s reviews and measurements of DACs, players, audio tweaks, etc. They are organized roughly into portable, non-portable and miscellaneous categories. I will update as I do more reviews.

[Organization and sorting courtesy of member @pozz. Much thanks.]

Please read through these two threads before checking the measurements below:
Articles & Studies

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...

Review and Measurements of Teac NT-503 Networked DAC

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Let me confess that I have had a man-crush on the look of the teac NT-503 for quite a while! :) Compared to a lot of utilitarian DACs that I test, the Teac looked so much nicer and professional in the pictures. Alas, at $1,000 retail price, I was reluctant to purchase it. Fortunately due to kindness of a friend of a member here, I received a unit for evaluation.

As noted above, the unit is quite handsome:

In person the rack handles are a bit much and get in the way a bit so could do without them. There is a handsome white LED/OLED that is informative and pretty. Menu navigation is through the handle in the middle and easy to figure out. Outputs are controlled through that which means it shuts off one or the other (RCA or...

Topping D30 DAC Measurement and Review

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Time for another bargain DAC, the Topping D30 DSD/PCM DAC. It retails for a mere $120 on Amazon including shipping:


I will do a hardware tear down later but for now, the enclosure seems nice quality and a step above typical DIY shops. The unit is externally powered and surprisingly with a Topping branded switchmode power supply. Typically people buy these in open market instead of having one made for them with custom label. It has higher than normal output of 15 volt which helps it with higher output drive as you see later.

Capabilities are excellent with PCM up to 192 Khz and DSD up to DSD128. Furthermore, the unit comes with not only USB input but also coax and optical S/PDIF inputs. Nice!

As always I started with J-Test to measure noise floor and jitter. For reference, I also test the Behringer UMC204HD, our king of low...

Behringer UMC-204HD Dac and Headphone Amplifier Review

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Previously I had reviewed and measured the Behringer UMC-204HD which retails for a paltry $79 with excellent results. See:

Question was asked about its headphone performance. So I setup a quick test, driving both my Audio Precision analyzer with 300 ohms (not ideal but good enough) and a pair of Sony MDRV6 headphones for subjective testing. As a comparison, I also put next to it the Exasound E32 which retails for $3,500.

Subjective results/listening test
I played one of my audiophile tracks and listened using my Z-series HP laptop in-built headphone out. Sound was good although at max volume, not deafening. I then switched to the Behringer. I had to turn up the volume on it to mid-position to get it to be louder than my laptop output. There, it provided a slight improvement in fidelity.

I then turned up the volume further and the fidelity went to hell...

Inside Your High-Res Music: Sound Liaison high resolution music clips

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Hello everyone. Here is another episode in my look inside different high resolution samples. Here, I analyze the free samples from the great indie label, Sound Liaison which as 2L, are kind enough to provide these clips for us to use:

In this look, I examine the DXD files at 352 Khz using another program, MusicScope:


This allowed me to play the files even in DXD and dsd formats.

As before, lots of surprises in this analysis. Issues in both DXD and DSD formats (especially the latter).

Exasound E32 DAC Review and Measurements

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I have been reviewing a lot of low cost DACs recently. I wanted to have a high-performance DAC as a reference. My best DAC is in my audio system and pain in the neck to relocate back and forth. So I set out to find a DAC in $2000 range (my cost). Idea was to have a very low noise/low distortion DAC that would be revealing of any tweaks put in front of them.

After getting suggestions from the forum, I short-listed it to Benchmark and Exasound. Both of them provide measurements on their site which gave me confidence of good design. As it turns out, I reached out to Exasound and they immediately answered so I went with them. I asked for accommodation pricing on E32 DAC and I received a good discount. As a professional courtesy I don't want to say how much that is. Suffice it to say it is similar to dealer margin for high-end products. Should this have been a transaction with someone I know, the discount is usually 10 to 20% higher. Still, I thought it was a reasonable...

Rocky Mountain Audio Fest (RMAF) 2017 Day 3 (Sunday)

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The third-day was a rather short one for me since the show closes early. But also because I attended an amazing presentation by Avalon as you will see later. It capped a very nice show and a relaxing one. I hope the show was successful for the organizers and it continues.

Rocky Mountain Audio Fest (RMAF) 2017 Day 2

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Here is my coverage of Day 2 of 2017 Rocky Mountain Audio Fest. As this was a full day, there was a lot more to cover. Hope you find it enjoyable and possibly informative.

Rocky Mountain Audio Fest (RMAF) 2017 Day 1

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Hello you all. So the day 1 at the Rocky Mountain Audio Fest (RMAF) came to a close. It was a calm and "orderly" day with little to gripe about :). Being part of the press, I did not have to wait in this line where last year they could not find my badge. :)


The line had died a few hours later.

The rooms had light to medium attendees. But when I asked a few companies what traffic they were seeing, they all said it was quite high and they were very satisfied with it seeing how it is not the weekend.

The weather outside is perfect with leaves starting to turn and super comfortable temps. But what the heck is going on here???

Monday is the day I fly out! How do we go from 70s to 30s with snow and then back to near 70s???? It does not compute!

Had great number of conversations with industry folks. Unfortunately i can't share much of it with you all. :D

Overall, nice, relaxing and...
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