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

Review and Measurements of Paradigm PW Amp

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This is a review and detailed measurements of the Paradigm PW Amp streaming capable power (speaker) amplifier. It is on kind loan from a member. The PW Amp normally costs US $499 but is being sold currently for just US $225 from company's website. Needless to say this has generated a lot of interest in the unit.

Due to use of class-d amplification and likely switching power supply, the PW Amp is quite compact and light:

Paradigm PW Amp Wireless Streaming Amplifier Audio Review.jpg

Please pardon the plastic over the controls. When someone send me a unit this way, I like to give them the privilege of removing it. :)

Beside the obvious controls, the one with arrow changes the input from streaming to back analog RCA and back. In use, I thought that when you streamed to it, it would take priority and play that input.

Here is the back panel:

Paradigm PW Amp Wireless Streaming Amplifier Back Panel Audio Review.jpg
Not wanting to mess with configuring Wifi, I did my testing using Ethernet port.

The speaker connectors are...

Review and Measurements of the HDPlex 200W Supply

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This is a review and detailed measurements of the HDPlex 200 watt linear, multi-voltage power supply. It is on kind loan from a member. The 200W costs US $485 from the company.

The enclosure is small but impressively hefty and quality feeling:

HDPlex 200 Watt Linear Power Supply Review.jpg

As you see, there are no controls or indicators in the front. The business end is the back:

HDPlex 200 Watt Linear Power Supply Back Panel Review.jpg


I was pleased to see so many concurrent outputs with two of them fixed and two programmable. For my testing, I only used the 5 volt output to power USB based DACs.

Use of an XLR connector is a bit unusual but is fine if one wires it up with heavier gauge wires. One adapter came with the unit that went from XLR female to 9 volt plug. That allowed me to test the unit with Topping D50. I also tested the 200W with Schiit Modi 3 DAC which requires a micro-USB cable. I managed to build an adapter to power that.

I wanted to test the 200W with my two best performing...

This audio cable business is getting out of hand...

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I got tired of using my long RCA cables to interconnect small DACs and Amps so decided to get a short one. Saw one on Amazon (by "World's Best Cables') that used Canare Star-Quad cable and Amphenol connectors for just $22 shipped. My time was worth much more than that to make one so I ordered it. It came promptly. When I opened though, I was shocked to see this massive sign in there:

Cable Direction.jpg


Are you kidding me? Even a low-cost cable using proper material spreads such a myth?

It is one thing to see this on multi-thousand dollar cables but on a $22 one?

Inside there is an instruction sheet and it says that again. To their credit they acknowledge that such burn-in will take out of Amazon's 30 day return window so they provide instructions on how to still get a return.

The danger here is that such practices will spread to the general public, not just high-end audiophiles.

Yes, it is also "directional" although here, it is due to the way they utilize the...

Review and Measurements of Nord One NC500 Amp

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This is a review and detailed measurements of the Nord One Hypex NC500 class-D module based power (speaker) amplifier. It is on kind loan from a member who recently purchased it. Nord is a British company so lists the cost of the Nord One as £ 979 or US $1,250 as of this writing. For that cost you get a pair of NC500 class-D modules from Hypex with dual PS1200 power supplies. I *think* this cost includes the stock input "buffer" (amplifier) from Hypex. You also have a choice of fancier, audiophile-type input buffer.

The Nord One comes in a very large enclosure (full 19 inch rack width):

Nord One NC500 Amplifier Class D Audio Reviews.jpg

A hard push button turns the unit on and off. Even with overdriving the unit, I could not get it to go into protection mode so not sure if such a feature is there or not.

The back panel has the bare minimum plus trigger sockets:
Nord One NC500 Amplifier Class D Back Panel Audio Reviews.jpg

The unit as it came had an issue. Can you spot it...

Review and Measurements of the Topping D70 DAC

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This is a review and detailed measurements of the new Topping D70 balanced audio DAC. The company was kind enough to send me a sample for review. The D70 costs US $499 although their products frequently go on sale.

The D70 has a similar look and feel to other Topping products which is to say feels quite solid:

Topping D70 Balanced DAC Audio Review.jpg

The display is now white OLED which gives the unit more of a professional look. Alas, even in its highest setting, it was not bright enough for my taste.

The back panel is what you expect with the addition of IIS port:
Topping D70 Balanced DAC Back Panel Audio Review.jpg
The D70 like the rest of the Topping products comes with full set of safety and emissions regulatory certificates which is important for a mains operated product. These certifications are expensive and add to the development time and hence the reason they are skipped in some other competing products.

The D70 comes with a new revision of their standard remote...

Review and Measurements of Peachtree Nova Pre

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This is a review and detailed measurements of the Peachtree Nova DAC and Preamplifier. It belongs to my son who bought it years back prior to upgrading to the Oppo HA-1. Peachtree site still show it as current but I don't think it is available in distribution now. It cost US $999 when it first came out I think.

If you are not familiar with Peachtree, they burst into the scene back in 2007 and due to clever online participation and marketing, became a huge success. I remember threads with thousands of posts on them and people would eat every word about newer versions of them and such.

The Nova Pre is one of the largest and heaviest DACs I have tested:

Peachtree Nova Pre DAC and Headphone Amp Audio Review.jpg

Some of the weight comes from the very thick, glossy finished case though. I had to take that apart to figure out why the line outs were not working. My son had...

Review and Measurements of Audio-gd DAC19 DAC

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This is a review and detailed measurements of the Audio-gd DAC19 DAC. It is on kind loan from a member who sent me two of their DACs for review. The DAC19 costs US $640 plus shipping from the company's website.

The design of DAC19 is similar to the rest of the Audio-gd line:

Audio-gd DAC19 DAC Audio Review.jpg

Controls feel solid and good. The unit also has good bit of heft to it so overall impressions are positive from a male perspective.

The back panel is what you expect plus a couple of their current-driven proprietary "ACSS" connectors:
Audio-gd DAC19 DAC Back Panel Audio Review.jpg
At this price range, XLR balanced output should be mandatory to help avoid ground loops which can readily occur with computer audio. It is missing here which is disappointing.

There have been many revisions of this model over the years. I think the original unit came out in 2010 and seems like that is the marking that is on the back of the unit. I am not an expert in all of that so...

Review and Measurements of Benchmark AHB2 Amp

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This is a review and detailed measurements of the Benchmark AHB2 Amplifier using THX technology to reduce distortion. I was going to request one for testing due to membership demand but to my pleasant surprise, the company volunteered to contact me and send not one, but two units! I requested the second one because of something I was seeing in the measurements that turned out to be my issue, not the amp's. The AHB2 retails for US $2,999 from the company direct.

The AHB2 is a very compact form factor, enabled by use of switching power supply to increase efficiency/density:

Benchmark AHB2 Amplifier Audio Review.jpg
There is just a power switch in the front. It might be but I constantly reached for the screw next to it to power it on! Having the power switch be slightly different color or shape may help with this.

There are a set of LEDs that show the status of the amplifier. They are driven by an FPGA (field programmable digital logic) that monitors all aspects of the...

Review of NanoPi NEO2: World's Smallest Audio Streamer

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This is a review and detailed measurements of NanoPi NEO2 tiny single board computer acting as an audio streamer. It was purchased and drop shipped to me by a kind member. It costs just US $19.99 although for some reason it is listed for $60 to $75 on Amazon.

The NanoPi NEO2 is one of the many variations of the Raspberry Pi single board computer. It gets its tiny size from elimination of the HDMI video output and some of the ports:

NanoPi NEO 2 Dietpi Roon Streamer Dashboard Audio Review.jpg

It is so tiny that I had to keep smacking the pink panther to keep it from eating it!

The low cost and small size is courtesy of Chinese implementations of ARM SoC (system on a chip) which you can see on the back:

NanoPi NEO 2 Dietpi Roon Streamer Dashboard Back Panel Audio Review.jpg

The "Allwinner H5" is the Soc sporting quad-core ARM processors. The NanoPi NEO2 has just enough peripherals for a "headless" (no display) audio streamer: gigabit ethernet port and one USB to connect to your DAC.

This is a blank slate: the...

Review and Measurements of Sony UDA-1 DAC & Amp

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This is a review and detailed measurements of the Sony UDA-1 DAC, headphone and power (speaker) amplifier. It is on kind loan from a member. It seems the UDA-1 was released back in 2014 with a retail price of US $799. Depending on the color, I see used ones around $350.

First impressions are positive on UDA-1 with a very hefty box and controls that feel nice:

Sony UDA-1 DAC and Amplifier Audio Reviews.jpg

There is no display but what is there is functional. Here is the back panel:

Sony UDA-1 DAC and Amplifier Back Panel Audio Reviews.jpg

Disappointed to see a fan in there for a box with such modest capabilities (rated at just 23 watts/channel). I had headphones on during testing so don't know how loud it gets.

Nice to see line in/out which makes my testing a lot easier as I can test the DAC and headphone/power amplifiers separately.

Note: I used to work for Sony in early 1990s so I have a soft spot for the company. Keep that in mind as you read this review.

DAC Audio...

Review and Measurements of Rane PS1 Phono Amp

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This is a review and detailed measurements of the Rane PS1 Phono stage/preamplifier. It is on kind loan from a member. It has been discontinued and seems to have come out circa 2002 (?). I can't find a price for it.

If you are not familiar with Rane, it is a company focused on pro audio and has written some of the best tutorials on audio. Needless to say, my expectations are quite high here with respect to the engineering of the PS1.

The PS-1 is an industrial looking thing:

Rane PS1 Phono Preamplifier Audio Review.jpg

The back panel makes you even less proud to put it on display:

Rane PS1 Phono Preamplifier Back Panel Audio Review.jpg

An external AC transformer with split tap powers the unit using a phone/RJ-11 style cable.

There are both unbalanced (RCA) and balanced (screw terminals) for output. I had to make a bare wire XLR cable to mate with the balanced output.

The shell of the balanced screw terminals was quite lose so I opened it to see what is going on...

Review and Measurements of Emotiva XPS-1 Phono Amp

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This is a review and measurements of the Emotiva XPS-1 Phono stage/pre-amplifier. It is on kind loan from a member. The XPS-1 costs US $199 from Emotiva or Amazon.

The XPS-1 looks and feels fantastic despite its bargain price:
Emotiva XPS-1 Phono Pre-Amplifier Audio Reviews.jpg

It reminds me of a very high quality piece of instrumentation than home audio gear. Shame that the form factor will probably relegate it to somewhere behind your regular audio gear.

The XPS-1 is powered by a 12 volt/0.5 amp universal switching power supply that is barely bigger than a mobile phone charger.

As you see, the XPS-1 supports both moving coil (MC) and moving magnet (MM) cartridges. There are a set of dip switches which seem to set the input impedance of the XPS-1. To wit, setting it to the lowest value of 47 ohm, severely reduced the output from my analyzer which has an output impedance of 20 ohm.

All in all, the XPS-1 nails the industrial design of a budget phono amplifier.

Phono Stage...

Review and Measurements of BSS BLU-BIB & BLU-BOB1 DAC/ADC

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This is a review and detailed measurements of Harman/BSS BLU-BIB 8 channel analog to digital converter (ADC) and BLU-BOB1 8 channel digital to analog converter (DAC). They are on kind loan from a member. The BLU-BIB retails for I think US $930 and so does the BLU-BOB1 but I see the latter on Amazon for US $790 and free shipping.

This is how the pair look:
Harman BSS Soundweb BLU-BIB and BLU-BOB1 Audio Review.jpg

I suspect most of you are not familiar with these two products. BSS is a company that Harman acquired a few years back. Their speciality is audio signal processing/DSPs that are easily programmed using their interactive software. The BOB1 and BIB are expansion output/input modules should you run out of ports on their DSB units. All products communicate using physical Ethernet link but not logical. That is, you can't talk to them from a computer but they communicate with each other over this link and can handle up to 255 channels of digital audio with sample rate up to 96 kHz...

Measurements of RME ADI-2 DAC and Headphone Amp

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I reviewed and measured the RME ADI-2 DAC a year ago. That was just prior to getting my new Audio Precision APx555 so the measurements don't directly compare to what I publish now. So a local member kindly loaned me his ADI-2 DAC to get fresh measurements.

If you are not familiar with RME ADI-2 DAC, it is a DAC-only version of the RME ADI-2 Pro. The former costs US $1,099 and the latter, US $1,999. It is an all-in-one DAC, headphone amplifier plus remote control. It has better connectivity with all the jacks in the back rather than dongle in RME ADI-2 Pro. The menu system is world's easier to navigate than the RME ADI-2 Pro. It has built-in parametric EQ and pretty spectrum display.

For the measurements, I took an abbreviated set but I think it paints the picture quite well.

DAC Measurements
Dashboard view is with USB input...

Audio: How We Hear

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Our resident technical and psychoacoustic expert and research/industry luminary, @j_j, recently gave a talk at our local chapter of Audio Engineering Society. He calls it Hearing 099. I tried to make it more descriptive and hence what is in the title. It is not very accurate but hopefully it is enough to get your attention. :)

I should tell you in advance that JJ's talk is a mix of very simple and useful information -- some summarized in just one sentence -- and others which will be complex and probably hard to understand for most of you. The simple messages are spread throughout the presentation so please set aside an hour and listen to it. And don't skip the last 5 minutes, whatever you do.


The talk will be the start of your understanding of our hearing system and likely something you will come back to often. It will also be a jumping point to learn more using other online resources. It is the best presentation I...

Review and Measurements of QSC DCA2422 Amp

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This is a review and detailed measurements of the QSC DCS2422 "Digital Cinema" Power Amplifier. It is on kind loan from a member. It must be sold through specialty channel as I can't find it available much. From the bit of searching I did, it seems to go for US $550.

This digital cinema characterization applies to the connectivity of the box. Otherwise this is a normal power amplifier in rack mount configuration:
QSC DCA2422 Digital Cinema Amplifier Audio Review.jpg

There is a nice dial with wide range of gains you can dial in. I liked the clipping indicator.

There is a speed controlled fan which is good. What is not good in home hifi situation is that even in its slowest mode there is a whine to the fan that is audible from 6 feet away. If you are going to use this amp, it would need to be in an equipment closet.

The back panel shows the locking SpeakON speaker connectors and only a pair of XLR inputs:

QSC DCA2422 Digital Cinema Amplifier Back Panel Audio Review.jpg

Given the programmable gain...

Review and Measurements of Monoprice Hybrid Tube Amp

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This is a review and detailed measurements of the Monoprice Hybrid Tube Power and Headphone Amplifier. It is on kind loan from a member who sent it to Monoprice to be fixed twice. It costs US $199 from Monoprice direct. I can't find it on Amazon but there is a "Rockville" amp that looks identical and it goes for even less at US $149.

When I first reached for this amplifier, I thought it was a high-end, $1000 headphone tube amp or something. Imagine by shock that it turned out to only cost $199 or even lower per above. They have nailed all the signature bling of a much more expensive amplifier:

Monoprice Stereo Hybrid Tube Amplifier Audio Review.jpg

In person it looks even better than it does in above picture (available light late at night). We have a rather heavy unit, with fine feeling volume control, VU meter and those signature rings around the tubes. Heck, it even came with plastic covering the plastic/wood looking sides! I don't understand the economics of these things at...

Review and Measurements of Pioneer VSX-LX303 AVR

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This is a review and detailed measurements of the Pioneer Elite VSX-LX303 Audio/Video Receiver (AVR). It was an impulse buy when it went on sale on Amazon a couple of weeks ago for US $369 including Prime shipping. It is currently US $399. I needed a replacement for my current Pioneer Elite AVR that is connected to our living room TV which is limited to 1080p.

From the outside, not much is changed compared to my Pioneer Elite:

Pioneer VSX-LX303 AVR Audio Review.jpg

The only improvement is the input selector dial on the left. On mine, it is very stiff. Here is loose and a bit easier to manage. The knobs are large but tactile feedback is poor. I guess they assume you are going to use the remote anyway. Still, I miss the large knobs on audio gear of the 1970s and 1980s.

When I purchased the VSX-LX303, I assumed it had an efficient class D amp like my current Elite. Alas, it does not. This is an issue for me as my current AVR is in a closed cabinet with not a whole...

Review and Measurements of Monoprice THX Desktop DAC & Amp

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This is a review and detailed measurements of the Monoprice THX AAA Desktop DAC and balanced headphone amplifier. It is on kind loan from a member. It costs US $480 from Monoprice direct including free shipping. The only other desktop headphone amplifier with THX AAA amplifier is from massdrop and it doesn't have a DAC, nor is it easy to find. So if the Monoprice performs, it will be a major win seeing how it also includes a DAC for only $80 more than Massdrop.

I previously tried to measure this unit when it first came but unfortunately it failed on my bench.

The industrial design is good:
Monoprice THX Desktop DAC and Balanced Headphone Amplifier USB Audio Review.jpg

The display looks a bit grainy to my eyes but it does the job. What doesn't is the volume control. It is digital which is fine. Not so fine is that it runs way behind the volume knob if you turn it quickly...

Vintage Audio: Measurements of Arcam Black Box 3 mk1

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As requested by @andreasmaaan here I made some measurements of an old DAC: the Arcam Black Box 3 MK1 which I bought new in 1991 (without MK1, see below). It retailed for around € 780 then (converted). Here are the front and the back:

arcam bb3 front.jpg

arcam bb3 back.jpg
It supports 44.1 and 48 kHz samplerate with 16 bits - that was the standard back then ...

Somewhere later around 1997 I fell victim to op-amp rolling and replaced the original op-amps (LM627CN) by OPA134PA. Two can be seen on this photo of the internals on the right PCB (audio mother board).The LF411 is used as DC servo. Two others are hidden on the backside of the left PCB (digital audio board). The result is my version MK1:

arcam bb3 intern.jpg


The measurements are done with REW, using an RME ADI-2 PRO fs, an old Edirol...
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