Articles, Reviews and Measurements of Audio Products

EVGA NU Audio Pro Review (Internal Sound Card)

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This is a review and detailed measurements of the EVGA NU Audio Pro 7.1 Surround DAC, headphone amplifier and ADC. It was kindly purchased new by a member and drop shipped to me. It costs US $300 on Amazon including free shipping.

I like the slick coloring and logo:
EVGA Nu Audio Pro Review PCI Sound Card.jpg


But I hate, hate, hate dealing with internal sound cards! This one even made me dig up a SATA cable for extra power! It took me half hour to get it into my gaming PC which had nice and neat cabling before I cut off all the tie-wraps to wire this thing. :( And this was just the main card. To get the surround channels, you need to insert yet another PCIE card in there:
EVGA Nu Audio Pro Review PCI Surround Sound Card.jpg


And then you need to put in a jumper display port cable to make the two talk to each other. By the time I was done, I was in bad mood but thankfully it all worked once installed their driver package. Unlike the bloatware that Creative ships, this one only had one piece of crapware which...

AKG K371 Review (closed back headphone)

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This is a review and detailed measurements of the AKG K371 closed-back headphone. I purchased this last summer and it currently costs US $149 on Amazon including shipping.

Note: our company, Madrona Digital, carries various Harman brand products although not the AKG products.

The K371 is made out of plastic but has a nice finish which belies its cheap structure:

AKG K371 Review.jpg


I especially like the feel of the pads. They are not huge but big enough to fit around my ears. Inside height of the pad is 2.51 inches. Inside width is 1.62 inches. With no depression, the pad depth to the driver is 0.8 inches. Outside diameter of the pad is 4 inches by 3 inches.

Three different cords are supplied which terminate into a 3-pin mini-XLR:

AKG K371 Review closed back headphone.jpg


Let me warn you about something I hate about these headphones: the headband adjustment mechanism. It either gets stuck and doesn't move at all. Or all of a sudden moves a bunch of notches. I...

ROLLS VP29 Review (phono stage)

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This is a review and detailed measurements of the ROLLS VP29 budget phono preamplifier. It is on kind loan from a member and costs US $49 on Amazon including Prime shipping.

I must say, very clever use of color and style for a budget case and price:

ROLLS VP29 Review Phono preamp.jpg


As you see, the unit is made in USA which is a rarity at this price.

Power naturally comes externally in the form of a DC 12 volt power supply:

ROLLS VP29 Review Phono preamplifier.jpg


There is a TRS connector on the left which we don't usually see. No wonder a lot of DJs seem to be using it based on Amazon reviews I read. Speaking of which, there are 551 reviews with average of 4.5 stars!

ROLLS VP29 Measurements
Let's see how the VP29 does on our usual dashboard made for moving magnet cartridges:

ROLLS VP29 Measurements Phono preamp.png


OK, this is puzzling. The FFT shows very little mains noise and distortion is down to -90 dB. So why on earth is our SINAD down to just 49 dB??? Something is going on...

Realistic 42-2101A Review (Vintage Phono Stage)

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This is a review and detailed measurements of the Realistic (Radio Shack) model 42-2101A phono preamplifier. It is on kind loan from a member and originally cost US $20 but I now I see a used one on ebay for $35.

The 42-2101 has the basic look of a lot of Radio Shack audio products:

Realistic 42-2101A Review Phono Stage.jpg


The thing that really got me was the text on the back:

Realistic 42-2101A Review Phono vintage preamplifier.jpg


Made in Japan for Radio Shack? Man, those were the days that Japan could make such products and still make money. Golden era of hi-fi to be sure....

Interesting that power supply is built-in. Everything today in this price range would have an external one. They went through UL certification and all.

Realistic 42-2101A Measurements
As usual we start with our dashboard:

Realistic 42-2101A Measurements Phono Stage Japan.png


Inclusion of AC power supply inside the unit is likely the cause of mains noise in there although some of the spikes are post rectification. Distortion is low at -90 dB. It is...

Lexicon DD8 Review (Multichannel Amplifier)

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This is a review and detailed measurements of the Lexicon, first generation DD8, 8-channel amplifier. It was purchased used by a member and drop shipped to me. The DD8 came from collaboration of Harman with TI (chip company) to produce very low weight, switching amplifiers for BMW car audio system. It was then later repurposed in this configuration for the Custom Integration (CI) industry. It is actually rebranded by a number of companies and sold under their label.

Note: our company, Madrona Digital, is a dealer for Harman products which includes Lexicon. So keep potential bias in mind as you read this review.

All 8 channels are provided in one compact, very cool running 1U rack mount chassis:

Lexicon DD8 Review Multichannel Amplifier.jpg


A stout on off switch manages power duties together with heftiest relay sound you have heard! The back will seem unusual for hi-fi market but is precisely what the custom integration channel needs:

Lexicon DD8 Review Multichannel Amplifier Custom Install.jpg


You can either...

Loxjie D50 Review (Stereo DAC)

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This is a review and detailed measurements of the Loxjie D50 balanced USB MQA DAC with Toslink, Coax and Bluetooth inputs. It was kindly sent to me by the company and costs US $720 on Amazon with free shipping.

The look and feel is similar to its sister company products:

Loxjie D50 Review Balanced USB DAC.jpg


The back panel has the usual connections we have come to expect in this tier product:
Loxjie D50 Review Balanced USB DAC XLR Toslink Coax.jpg


The unit feels quite solid giving a feeling of quality (again, typical of high-end desktop DACs).

Loxjie D50 Balanced DAC Measurements
As usual, we start with our dashboard of 1 kHz tone, sending bits via USB and extracting using balanced XLR outputs:

Loxjie D50 Measurements Balanced DAC.png


As you see, performance is exemplary with SINAD that represents relative sum of distortion and noise outperforming 95% of DACs tested so far:
Best balanced USB DAC Review.png


Zooming in we get:

Best high-end DAC review.png


D50 can output higher voltage though and if allowed, it...

$9 Headphone Review: Sony MDR-ZX110

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This is a review of Sony MDRZX110 to figure out if a US $9.99 headphone on Amazon including Prime shipping has good performance. There are over 45,000 reviews on Amazon averaging 4.5 stars saying it has that. But let's find out!

I must say, as cheaply as the Sony is made, it doesn't look like kids toys as some do in this price range:

Sony MDR-ZX110 Review Budget Headphone.jpg


The pad kind of feels luxurious if you lower your standard somewhat:

Sony MDR-ZX110 Review Budget Padding Headphone.jpg


Due to very low eight (about 4 ounces) and rather soft pads, I found the MDR-ZX110 quite comfortable to wear. After just a few minutes you forget about it. It is certainly more comfortable than much larger headphones. There is a bit of sound isolation which was enough to get rid some of the high-pitch whine from my PC's fan. This obviously will different depending on your ears.

Naturally this is an on-ear headphone which should make it "fun" to measure.

Note 1: The measurements you are about to see are...

Paradigm Prestige 15B Review (bookshelf speaker)

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This is a review and detailed measurements of the Paradigm Prestige 15B bookshelf speaker. It was kindly purchased by a member and drop shipped to me. The retail cost is US $799 each. Before writing the review I thought that was for a pair. Note that this is sold through dealer channel so actual cost may be lower.

The 15B looks really sharp with fair amount of class:

Paradigm Prestige 15B Review.jpg


Same is reflected even on the back with custom port flange and binding posts:

Paradigm Prestige 15B Review back panel binding posts.jpg


Speaker also feels fairly dense and heavy. I have zero complaints about the look and feel of the 15B.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it...

Why are all tweeters 1 inch in diameter ?

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Sorry for the dumb question but i always wondered why all tweeters are 1 inch?
Let's say they will make it 2-3 inches, will it sound better?

XTZ EDGE A2-300 Review (amplifier)

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This is a review and detailed measurements of the XTZ A2-300 class D amplifier. It is on kind loan from a member and costs US $500 from the company direct (which is located in Europe). It is based on B&O ICE 300ASC or its newer name, 300A1.

While you won't mistake the enclosure for A2-300 as a high-end, custom design, it has enough extra touches to set it above typical DIY type cases:

XTZ A2-300 Review Class D Amplifier.jpg


There are some nice looking vents on the side. Note however that all the heat is centralized in the center bottom panel as is typical of class D amp modules. In use though, the bottom barely got warm although I could smell heat generation through side vents.

I was disappointed to not see balanced inputs:
XTZ A2-300 Review Class D Amplifier back panel.jpg


The gain potentiometer will make the unit flexible but they are typically not good for reliability. Since these controls don't get used often, then tend to go bad. If you buy this unit, be sure to turn the control left and right...

Dan Clark Audio AEON RT Review (closed headphone)

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This is a review and detailed measurements of the Dan Clark ÆON RT closed back headphone. It was kindly sent to me by the company for testing and costs US $500.

In a sea of similar looking headphones, the ÆON RT manages to distinguish itself with a uniqe shape:

Dan Clark Audio ÆON RT  Review.jpg


This makes the cup smaller which can be good for travel although I find that it almost touches the top of my ears. Clamp pressure is a tad high for my head causing a bit of strain after a few hours of use.

The pads feel soft and luxurious. A set of filter pads are supplied that get mounted inside to control the level of high frequencies. A white pad with one notch comes installed. I took it out as it attenuates too much of the high frequencies and likely causes some slight comb filtering as well.

The supplied cable is rather soft for this type of cord and comes with nice click on, 4-pin connectors for each side:
Dan Clark Audio ÆON RT  Review Cable.jpg


The headband is infinitely adjustable and is...

Fiio M15 Review (Digital Audio Player)

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This is a review and detailed measurements of the Fiio M15 DAP. It is on kind loan from a member and costs US $1,300 including Prime shipping on Amazon.

The M15 runs Android but also has a dedicated, player mode (which I did not test). It feels substantial like most DAPs:

Fiio M15 Review DAP Digital Audio Player Balanced.jpg


When I powered this unit up, I was pleasantly surprised by owner's installation of Roon. Fired that up and found it quite nice to have for around the home given the fact that I am a Roon user. Alas, while there was some kind of upgrade going on, Roon constantly stopped and could not fetch my music. So performance -- Wifi or CPU -- is not that great or at least anything getting close to a modern mobile phone.

I don't know which version of Android it is running. I had a hard time navigating it as I could not figure out the back button, etc. Not a huge deal but was not as close to my regular phone as I wished. This is as much Android's fault as is Fiio's.

Nice suite of jacks...

SMSL SP400 Review (headphone amp)

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This is a review and detailed measurements of the SMSL SP400 balanced THX headphone amplifier. It was kindly sent to me by one of their dealers, shenzhenaudio. It costs US $630 from them.

The SP400 makes an attempt at luxury with glossy plexiglass top and digital display:

SMSL SP400 Review balanced headphone amplifier.jpg


As you see, there are no controls on SP400. Everything is menu driven including input selection and gain. If you use multiple headphones with different gain requirements, having to switch that using the menu can be a bit of a hassle. Fortunately there is a mitigating factor as you will see in the measurements.

One main distinguishing feature is that there is remote control and relay based R2R implementation. This should assure very good channel balance -- something that we will check later. It costs a lot to implement this feature though and that is...

Abyss Diana V2 Review (headphone)

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This is a review and detailed measurements of the Abyss Diana V2 open-back planar headphone. It is on kind loan from a member and costs US $2,995. You get to choose your cable length and type which can add another $50 to the cost.

The Diana V2 is extremely light and has exquisite build and attention to detail:

ABYSS Diana V2 review open back headphone high-end.jpg


It almost melted on my head as soon as I put it on, getting very close to perfect for me. Note that the test sample has an aftermarket pad on the headband:

ABYSS Diana V2 review open back headphone headband pad.jpg


Without it, it may have been less comfortable. I see reports online saying the paint chips easily which if so, would be a serious concern in this price range.

The pads are very soft and attached with powerful magnets and four pins so you can rotate them or change them for another (I have the "DMS" pads which I may test next).

The softness of the pads presented serious challenges in measurements. Mere lifting them and letting good would change bass...

Philips Fidelio X2HR Review (headphone)

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This is a review and detailed measurements of the Fidelio X2HR open-back headphone. I bought mine on sale for US $116 but current price is US $145 including Prime shipping on Amazon.

The X2HR reminds of Grado headphones if they grew double in size and substance:

Philips Fidelio X2HR review open back headphone.jpg


Let me warn you that if you have any insecurities about losing your hair, it going gray or both, this is NOT the headphone for you as the pads gather any such falling hairs! :) Otherwise, this is a very comfortable headphone with large cups. The elastic band on top eliminates the need for adjustability and reduces moving parts.

A long, stiff and microphonic cable comes standard with it:

Philips Fidelio X2HR review open back headphone stiff cable.jpg


Fortunately the cable uses standard 3.5 mm connectors so you can use your favorite replacement.

Overall my impression of design, feel and usability is positive especially for the price.

Note: The measurements you are about to see are preformed using...

Graham Slee Reflex C Review (phono stage)

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This is a review and detailed measurements of the Graham Slee Reflex C phono preamplifier. It was kindly sent to me by a member and costs US $1,240 (695 pounds in UK). This is the first moving-coil-only phono stage I have tested. Usually they are either moving magnet only or both.

The case is a DIY type affair albeit, with rather attractive coloring and graphics:

Graham SLEE Reflex C Review Moving Coil Phono Stage.jpg


Back panel brings no surprise:

Graham SLEE Reflex C Review Moving Coil Phono Stage Inputs.jpg


What is surprising -- and I forgot to take its picture -- is the mass external power supply. It is larger than Reflex C itself and has an odd shape rather than the usual rectangle. It is also DC rather than AC. Not sure why they did not opt for a transformer and use AC input and put the DC conversion inside.

The moving-coil only feature set put a twist in my work as I have not captured competitive data on this input. So the following measurements are provided as they stand.

Graham Slee Reflex C Measurements
As...

Elac Uni-Fi 2.0 Review (bookshelf speaker)

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This is a review and detailed measurements of the Elac Uni-Fi 2.0 bookshelf speaker. It was kindly sent to me by a member and costs US US $600 a pair on Amazon including Prime shipping.

This review will be abbreviated for reasons that will become apparent later.

Here is a shot of the speaker:

Elac Uni-Fi 2.0 Review Bookshelf Speaker.jpg


Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the...

Superlux HD668B Review (headphone)

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This is a review, detailed measurements and equalization of Superlux HD668B semi-open headphone. It was kindly purchased by a member new and drop shipped to me. It costs as little as $40 including free shipping on Amazon.

Needless to say, you are looking at all plastic headphone here:

Superlux HD668B Review cheap Semi-open Headphones.jpg


It looks like you can adjust the headband but you can't. Trust me, I tried at first. :) the little pads on top are supposed to be a self-adjusting mechanism. They kind of work but then put pressure on two small spots on your head.

The cable terminates in a male connector which is unusual:
Superlux HD668B Review cheap Semi-open Headphones removable cable.jpg


The cups are on the larger side which helps a lot with comfort given the stiff spring action. I would give it an 80 to 90% comfort after you wear them a few minutes.

Superlux HD668B Measurements
Here is the HD668B frequency response:
Superlux HD668B Measurements Semi-open Headphones.png


We see good adherence to our target curve from 70 Hz to 2.5 kHz which is good...

Lavaudio DS600 Review (Stereo DAC)

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This is a review and measurements of the 1mii Lavaudio DS600 USB DAC. It was kindly purchased new by a member and drop shipped to me. It costs US $225 including Prime shipping.

The DS600 enclosure feels quite solid and substantial (i.e. machined out of a block of aluminum):

Lavaudio DS600 Review USB DAC.jpg


There is some talk that the DS600 may be a copy of Topping D50s. It indeed looks very much like it but with addition of that headphone jack. The display looks sharp and nice (better than the picture) but did not come with a plastic cover. I also saw a spec of dust behind the front glass.

Back panel is what you expect:

Lavaudio DS600 Review back panel.jpg


A USB cable to 9 volt barrel connector is supplied and is mandatory to power the unit with any port (including USB).

When It tried tried to configure the DS600 for testing, I saw this odd indicator...

NAD Viso HP50 Review (headphone)

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This is a review and detailed measurements of the NAD HP50 headphone. It was kindly purchased new by a member and drop shipped to me. While NAD still lists this headphone, it doesn't seem to be available at retailers. Instead, there are some being sold on ebay. I think new they were going for $300 but ebay seller has certified refurbished for $179 normally. But apparently they frequently go on sale down to just $89 which is what the member paid. The packaging and headphone look brand new so they must be clearance stock.

I like the modern look of the headphone:

NAD Viso HP50 Review.jpg


Notice how the two cups are hanging differently from each other. This is because the headband is not symmetrical. This, combined with rather small cups made getting consistent results between the two channels impossible. Also, when you expand the headband, it will become rather square, giving you a Frankenstein look. My monitor is not reflective so I was good with that!

An...
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