Articles, Reviews and Measurements of Audio Products

Review and Measurements of Cambridge DacMagic Plus

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This is a review and detailed measurements of the Cambridge Audio DacMagic Plus DAC and "digital pre-amplifier." It is on kind loan from a member and costs USD $349 from the company itself or Amazon with Prime shipping. Researching the unit, it seems to have come out around 2012. Yet it seems to still be a current unit seeing how Cambridge still sells it.

The industrial design of the DacMagic Plus falls in line with the rest of Cambridge Audio products which is somewhat understated but fine looking nevertheless:

Cambridge Audio DacMagic Plus Review.jpg

This is called a digital preamplifier because it has multiple inputs and a volume control. There are also selectable output filters and a headphone out. I did not test the headphone output because it seems to have pretty high output impedance.

Back to volume control, it has a horrible feel. It is a rotary encoder meaning its value is digitized and used. As such, it has no minimum of maximum like an analog control...

Review and Measurements of Spectra X DAC & Amp

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This is a review and detailed measurements of the NextDrive's SPectra X Dac and Amplifier USB dongle. It was sent to me by the company and costs $USD 189 including Prime shipping on Amazon. Clearly this is a lot more money compared to $9 dongles from likes of Apple and Google.

The spectra X makes a very good first impression as dongles go:

NextDrive Spectra X DAC and Headphone Amp Review.jpg

It is far more robust than the flimsy phone dongles. It is a metal tube and feels nice in the hand.

The Spectra X comes with different end connectors. I asked for the USB-A version so I could test it using my computer.

Spectra X was UAC2 compliant meaning you don't need driver. In my case though I got bit by the ASIO4ALL wrapper issue where the device for some odd reason shows up as a 16-bit device. NextDrive provides a set of drivers but it quickly quit saying I already have a more up to date eversion of "bravo HD" driver. I tried to use that but it quickly hung my Audio Precision analyzer...

Review and Measurements of Fiio K3 DAC & Amp

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This is a review and detailed measurements of Fiio K3 DAC and portable headphone amplifier. I got talked into buying it earlier this month due to popular demand. Fo you all's sake, it better measure well! :D

The Fiio K3 is quite cheap for such a combo product and costs just USD $109 including Prime shipping from Amazon. As such, if it works out, it will be killer combo as far as price is concerned.

The first impressions are positive with the nice but very small looking enclosure:
Fiio K3 Portable DAC and headphone amplifier Review.jpg

We see the typical gain switch and bass boost. Unusual in this price class is having a "balanced" output which in the case of headphones, just means potential for higher output power. Please don't confuse this with balanced inputs which provides high level of ground loop immunity. Balanced output doesn't provide such benefit.

The volume control is a rather unique implementation where an analog control is used with min and max (unlike rotary controls that keep turning)...

Review and Measurements of Fiio K5 Headphone Amp

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This is a review and detailed measurements of Fiio K5 headphone amplifier. I purchased this unit last fall and it has been sitting patiently for a review. The K5 costs USD $110 including free shipping from Amazon. What is unique about this product is that it has a dock mechanism to mate with the USB connector on Fiio portable audio players:

Fiio K5 Headphone Amplifier Review.jpg
By flipping the gray door on top of the unit different Fiio players can connect to it. You can then select that input with the front panel switch. In the back there is a USB jack that routes to the portable player, allowing it to be used as DAC. Without it, there is an analog-only amplifier with NO DAC built-in.

The case is metal but it has a paint on it that is normally is used to make cheap plastic look like metal. As such, it looks rather cheap to me. The volume control feels nice though. And it is fairly hefty so sits there without the cables pulling on it.

Power is provided by a...

Review and Measurements of Lyngdorf RoomPerfect EQ

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This is a follow up to my review of the Lyngdorf TDAI-3400. While that review was focused on objective measurements of the DAC and amplifier, this review is focused on the performance of the room equalization (RoomPerfect). As much as I like to perform a comprehensive test and review of Lyngdorf against a few of its competitors, I just don't have the time to do that. So instead this is a focused test by itself.

I usually don't want to mess up my my main system because it takes me forever to get it back together. In this case I thought it was important to test the Lyngdorf using the same setup given the high cost of the Lyngdorf. At first I was dreading how much rewiring I had to do, only to realize that the Lyndrof has everything my discrete system has sans speaker! So this is the setup:
Lyngdorf TDAI-3400 RoomPerfect Review.jpg

I took a rather wide shot so...

Review and Measurements of Lyngdorf TDAI-3400 Amp & EQ (Part 1)

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This is part one of the review and detailed measurements of Lyngdorf TDAI-3400 Integrated amplifier, streamer, DAC and Room equalizer. It is on kind loan from a member and costs USD $6,499 (£4,995.00). In this review I will be focusing on the overall features of the unit, and performance of its DAC and amplifier subsystems. In part 2 I will be hooking it up to my main system to test the RoomPerfect room equalization feature.

Note: My company, Madrona Digital does business with one of the companies in the Lyngdorf family (Steinway Lyngdorf). I consider them a good partner of our company so feel free to read as much or as little bias as you feel is right into my review.

The TDAI-3400 is of course quite expensive relative to typical desktop systems we test but one look at the outside and you can take comfort that you purchased a luxury audio product:
Lngdorf TDAI 3400 DAC Room EQ Audio Processor and Amplifier Review.jpg

If you are not familiar with Lyngdorf, it is one of the earliest pioneers of...

Review and Measurements of NAD M51 DAC and Digital Preamp

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This is a review and detailed measurements of NAD M51 DAC and digital preamplifier. It is on kind loan from a local member. Even though it is still listed on NAD website, other retailers indicate it is discontinued. Looking around, it seems the cost is USD $2000.

The unit has somewhat bland industrial design for my taste:

NAD M51 DAC and digital Pre-amplifier Review.jpg

What distinguishes the NAD 51 from many other DACs are two things 1) custom upsampling DAC and 2) HDMI inputs.

On the DAC portion, this is how NAD describes it:


In simpler terms, the sample rate of content is increased to 844 kHz and then what resembles a little class-d amplifier converts it to analog. The higher sample rate reduces the needed bit depth/accuracy in the PWM portion of the DAC. Whatever DSP they use, must have a 35-bit word length and hence the reason that is the accuracy of the volume control.

The second feature, HDMI is something that is very rare in DACs. In...

Review and Measurements of Bluesound NODE 2i Streamer

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This is a review and detailed measurements of the Bluesound Node 2i Streamer. It is on kind loan from a member and costs $499. I am assuming their target market is where SONOS dominates if you are familiar with that brand.

From the outside, this is one looking and feeling unit!


The unit is pure white with a luxurious rubberized paint. It ranks way up there as something Apple would design.

It is mains powered with a removable 2-conductor cable.

It has both wireless and wired connectivity. I tested it with the latter. Being a network-centric device, the only digital input is a combo 3.5 mm Toslink optical input. For output though there is S/PDIF coax and Toslink optical digital outputs. Analog outputs is a set of RCA for left and right plus a subwoofer output.

There is external IR input for integration in home automation although I hope it also has IP control (have not checked).

There is no display on the unit. The only...

Review and Measurements of Wireworld Starlight 7 USB Cable

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This is a review and detailed measurements of Wireworld Starlight 7 flat USB cable. It is on kind loan from a member. The cost is USD $100 including Prime shipping for the 1 meter/40 inch length I am testing. For this review, I compared it to my current favorite, the 6 foot/1.5m version of Amazon Basics USB cable which costs USD $5 with Prime shipping included. Yes, quite a price difference!

The Wireworld Starlight 7 comes in bright red color with nice indicating its UL rating and such:

Wireworld Starlight 7 Flat USB Cable Review.jpg

It has the usual buzzwords of OFC, Silverclad, "Symmetricon design," etc. And of course some fantastical claims such as this one:

"For a 5 STAR enhanced performance experience from gaming to videos, music to movies, rendering to data, downloads and publishing… better cables = broader bandwidth and faster data transmission speeds."​

Faster transmission speeds? I don't think so. In this short length any non-broken USB cable will...

Review and Measurements of Matrix Audio X-SPDIF 2 USB Converter

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This is a review and detailed measurements of the Matrix Audio X-SPDIF 2 USB to S/PDIF and I²S (IIS) converter. It is on kind loan from member who also sent me the Wyred4Sound DAC-2v2 SE DAC. The X-SPDIF 2 costs USD $379 but the company is selling for reduced cost of USD $341.10. Some complicated math must have gone into that computation to come up with that extra 10 cents in the price! :)

The S-XSPDIF 2 comes in a small but very heavy enclosure. You can see it almost lost in the pool of gear I had to use to test its capabilities:

Matrix Audio X-SPDIF 2 USB to SPDIF and I2S Converter Review.png.jpg

It is the non-descript box on top of the Wyred4Sound DAC. To the right, is the Wyred4Sound PS-1 multi-voltage power supply. It has modules you buy that give you different output voltages. The owner supplied that so I tested with and without it as the X SPDIF-2 can run on...

Review and Measurements of Dayton Audio APA 150 Amp

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This is a review and detailed measurements of the Dayton Audio APA 150 power (speaker) amplifier. It is on kind loan from a member. It costs USD $168 from Parts Express including free shipping. If the specs of 75 watts/channel are true, you are getting a stereo amplifier for about $1 per watt! Amazing how cheap these amplifiers have gotten.

The APA 150 is a chunky unit, departing from the typical wide cabinet format:
Dayton Audio APA 150 Power Amplifier Review.psd.jpg

As you see, there is a volume control so you can skip a preamplifier if all you have is one input. In the back, there are switches for bridging to mono, filtering and auto on.

The unit is fan cooled but it is temperature controlled and quiet.

The design is the classic class AB with a linear power supply which makes the unit heavy and inefficient. So good to see the fan there to keep things cool.

There are serious looking ETL/CE safety and regulatory markings on the unit which I take to be genuine and provide peace...

Review and Measurements of DarkVoice 336SE Headphone Amp

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This is a review and detailed measurements of the DarkVoice 336SE pre-amp and headphone amplifier. It is on kind loan from a member who has literally been waiting months to get it reviewed! It costs USD $310 on Amazon including free shipping. It has 42 reviews summing to 4.5 stars on Amazon so customer satisfaction must be good.

This is one beast of a headphone amplifier with a massive transformer and large chassis weighing it down:
DarkVoice 336SE OTL Tube Headphone Amplifier Review.jpg

Up to now we have tested hybrid tube headphone amplifiers that use tubes as the first stage but drive the headphones using transistors. That allows the output impedance to be as low as solid state amplifier yet give you the "benefits" of tubes, whatever they may be. In DarkVoice 336SE, the signal path is all tube. The configuration is OTL meaning Output-Transformer-Less. A tube amplifier needs to block high voltage DC from going out of the unit and also reduce the rather high output impedance of...

Review and Measurements of Aune X1S DAC & Amp

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This is a review and detailed measurements of Aune X1S DAC and headphone amplifier. It is a kind loan from a member who has waiting for its review since last fall! The X1S seems to be have been out for a while, having found a review of it going back to 2015. It is still available though and costs USD $259 from Amazon including prime shipping. This is nice since US customers at least don't have to wait for it to arrive from China and early customer support issues can be resolved by just returning it to Amazon.

Aune has its own "design language" which I like. It shouts "high-end" even though the price is in budget category:

Aune X1S DAC and Headphone Amplifier Review.psd.jpg

The unit has the matt/fine textured finish that is popular these days and picks up smudges easily. I had to touch up the above in photoshop fair bit even though I cleaned the unit prior to taking the picture with a microfiber.

As you see, the input is rather plain with an analog volume control and an input...

Tube Rolling of Schiit Saga Pre-amplifier

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This is a performance test of the Schiit Saga pre-amplifier using two different tubes. The unit and extra tubes are on loan from kind member. See the review of Schiit Saga in parallel thread.

As I mentioned in the review of Saga, the stock tube is a Russian made clone of 6NS7 which goes by label of 68HC. The extra tube provided is from Raytheon and was made in USA. You can see them side-by-side here:

Schiit Saga Hybrid Tube Passive Pre-amplifier Tube Rolling measurements.png.jpg

The 68HC is on the left and the Raytheon 6SN7 is on the right.

The pins on the 68HC had some oxidation on them. In contrast the pins on the Raytheon 6SN7 were pretty clean.

I did not repeat the measurements of 68HC. I just ran a few of the tests on 6SN7. So there be some variation in performance of the unit overall but hopefully that is lost in the noise, pun intended.

Let's get into measurements and...

Review and Measurements of Schiit Saga Tube Pre-amp

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This is a review and detailed measurements of the Schiit Saga passive/tube pre-amplifier. It is on kind loan from a member who has waiting literally months for his review! The Saga costs USD $349 from Schiit direct with stock tube plus shipping. The tube supplied with this unit was the Russian 68HC which is their clone of 6N8S (dural triode).

The industrial design is typical of Schiit product but as usual, with a different switch mechanism and looks:

Schiit Saga Hybrid Tube Passive Pre-amplifier Review.psd.jpg

For reasons too embarrassing to explain, I had to open the unit and there, I noticed the analog volume control (which gets converted to digital), had a nice notch on it. I was happy they were using such as that would avoid the volume control becoming loose, only to realize the set screw goes on the round part of the shaft, not flat! :facepalm:

Anyway, back to the switches, the are microprocessor controlled and feel nice. Click the input one on the left and you rotate between five...

Review and Measurements of Wyred4Sound DAC-2v2 SE DAC

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This is a review and detailed measurements of the Wyred4Sound DAC-2v2 SE. It is on kind loan from a member. The cost of the unit is USD $3,800. The one under test also has the "femto clock" option. I don't see a price for that even though it is shown as an option.

The unit itself is narrow but quite deep and heavy for its functionality:

Wyred4Sound DAC-2v2 SE DAC Review.jpg

The SE version is an upgraded unit with the following:


Yes, even an upgraded fuse!

I am not too happy to see a small and difficult to navigate interface in high-end devices. For this much money, give a nice display with dedicated buttons for things like setup please. And I like to see all the settings displayed and not crypting dashes and brackets.

There is an included remote which is nice. Not so nice is the rubberized finish that has become sticky. This happens when the finish degrades after many years. I don't think this unit is that old so surprised that it...

Review and Measurements of Grace Design m900 DAC & Amp

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This is a review and detailed measurements of the Grace Design m900 DAC and headphone amplifier. It is on kind loan from a member and was drop shipped to me. It costs USD $575 but I see it on sale for USD $545.

The unit has a substantial feel to it despite being small. Its design highlight is the metal rotary control for the volume control:
Grace Design m900 DAC and Headphone Amplifier Review.jpg

The rotary control feels a bit light to me but otherwise, it is one of the best controls in the business. Unlike similar looking ones from JDS Labs, this one has a metal knob giving it more of a luxurious feel. A couple of bright white LEDs show the current volume level as you see in the picture.

The unit comes with an optional external USB power supply which is beefier than the typical mobile phone one. The manual says it will work without it but it will sense the lack of sufficient current from the USB port and throttle the output. For my testing, I left the power supply plugged in...

Review and Measurements of NuForce DAC80

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This is a review and detailed measurements of the Optoma NuForce DAC80 DAC. It is on kind loan from a member who has been patiently waiting for it from November of last year! :) This a rather older DAC (in "DAC years") having been introduced back in 2016 with a retail cost of USD $549. Massdrop put this up for sale in 2017 for USD $331 which is how the owner acquired it.

The box is decent enough from the outside:

Optoma NuForce DAC80 USB DAC review.jpg

To turn on the unit you have to push the volume control in. Doing the same while on selects the input. Turning off requires holding down the button. All standard methods but not the indicator of which input. As you see, there is some attempt at using an array of LEDs to indicate the input by a letter. Alas, these are pretty dim and hard to see in bright light. It is a bit of differentiation which I don't think is worth the cost.

The volume control is rather strange feeling. It has limits so it is an analog control...

Review and Measurements of Neurochrome Modulus-286 Amp

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This is a review and detailed measurements of the Neurochrome Modulus-286 Power (speaker) amplifier Kit. It is on kind loan from company designer and member, @tomchr. It is to ship by end of this month and costs $1,299. See:

As you may recall from my review of Tom's headphone amplifier, Neurochrome designs strive for very low distortion and good, objective performance. So I have been quite excited and anxious to measure one of Tom's power amplifiers.

From the outside, the Modulus-286 is rather small but very chunky look with massive heatsinks (for its size) on each side of the unit:

Neurochrome Modulus-286 Power Amplifier Review.jpg

The heart of Modulus-286 and other solid state amplifiers Tom designs are the integrated LM3886 IC from Texas Instruments. I suspect this is from the National Semiconductor team though which was acquired by TI.

The LM3886 is a pretty powerful little IC capable of...

But what is the Fourier Transform? A visual introduction.

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