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

This is a review and detailed measurements of the Nobsound MC-103 Pro 3-IN-1-OUT XLR Audio Switcher. The unit I have came with the brand Douk on it so that is what I used in my notations below. I suspect multiple companies put their name on it. I purchased it a few days ago from Amazon. The MC-103 Pro costs US $59 from Amazon including Prime shipping.

This is a sturdy but small box with a large input selector on it:


The selector has a scratchy feel to it but does the job. The box is too shallow to be able to control the heavy XLR cables I was using with it so had a tendency to tilt back.

The back has just the connectors you would expect:

This is a passive selector/switch so there is no need for power. As such, it should be bi-directional although I just used it as three inputs and one out.

Selector Audio Measurements
As usual we start with our dashboard with 4 volts in, and...

This is a review and detailed measurements of the JBL M-Patch Active 1 USB DAC/ADC, analog switcher and headphone amplifier. I bought summer last year and just now getting to review it. I don't remember what it cost then (it was special on some site) but it is US $100 on Amazon. But get this listing:


Just imagine the level of confusion at JBL to be listing this device as a set of four casters. Anyway this was a product from another company that JBL acquired. Original price was US $200 I think. Lost in the midst of giant Samsung/Harman it may be liquidating prices.

The unit looks like above in person:

Volume control is smooth and has no detents. The switches are quite stiff to push. Given the application (live music/speech) having stiff switches so you don't change settings by accident is probably a good thing. It is a loss for my use though in that they are not toggle switches...

This is a review and detailed measurements of the Neumann KH 80 DSP Active Monitor (speaker). It was kindly sent to me by a member. The KH 80 costs US $500 each which is quite pricey for a small speaker.

And small it is:


Unfortunately there is no good sense of scale above but let me emphasize that these are quite small speakers.

Here is a shot of the connectivity and controls:


The power connector is a figure-8 socket on the left tunnel beside the power switch. I appreciate the skinny flexible cable. Likewise the XLR/TRS combo socket is on the right. This way, you can wall mount the speaker and not worry about the wires. This also meant that I had a hell of a time getting my signal cable out of that narrow channel. I literally had to get a pair of needle noise pliers to pull them out.

There is an Ethernet like socket which with some "hub?" you can connect to an iPad and only an...

This is a review and detailed measurements of the Auralic Leo GX "atomic clock" outboard option for the Vega G2 that I just reviewed. It is on kind loan from a member. The LEO GX costs US $8,299.

The LEO GX comes in the same enclosure as the Vega DAC:


Strangely for a device that just produces a clock pulse for the DAC, the thing goes through a lengthy boot process and "loading applications." Likely it is the same OS as the DAC and is there to manage the display and such.

A one hour count-time timer is shown on the display. The clock source is "oven" controlled and they are waiting for it to reach target temp. The unit works immediately though so you don't have to wait for that.

The back panel shows more connectors than you would expect:


In addition to the coax...

This is a review and detailed measurements of the Auralic Vega G2 Network Streamer and DAC. It is on kind loan from a member. The Vega G2 costs US $6,599. The owner supplied an external clock for it which I will review separately.

The Vega G2 is exceptionally heavy for streamer/DAC:


I did not however care for the super sharp edges and corners.

The display is large, high resolution and attractive. It nicely shows the volume level, sample rate and filter settings. The general user interface is OK. I managed to get through it.

The back panel shows a lot of connections as it should in this price category:

Boot up time was high when network connection was live but this is typical of other streamers.

I initially tested the unit using stock Windows 10 driver and ASIO4ALL wrapper. Alas, in this mode there were data transfer issues so I downloaded their drivers which had a nice, working...

This is a review and detailed measurements of the Singxer UIP-1 USB Isolator and "Purifier." It is on kind loan from a member. The UIP-1 costs fair bit at US $259.

The box while utilitarian is a step above budget category:


The connectivity is simple enough:

For operation the UIP-1 needs an external power supply as you can see from the connector on the left. Strangely, none came with it! I am assuming they are thinking (perhaps correctly) that the market for this is audiophiles would be using fancy linear power supplies and such. For my testing, I used my Keysight/Agilent lab power supply at 7 volts.

The guts show an off-the-shelf USB isolator:



The white band is a required design practice to fully isolate the "dirty" and clean sides of the USB bus. The number (maxim 4930?) seems...

This is a review and detailed measurements of the Yamaha HS5 Powered Monitor (speaker). I purchased it this afternoon for US $200 which is the price that it goes for everywhere. This is for a single unit by the way.

The industrial design of the HS5 is fantastic:

Get the larger ones and I am sure you can charge another $10/hour for your mix.

Fit and finish seems nice with a solid single enclosure encompassing the baffle (front and surround).

Here is a shot of the back:

I have not read the manual but while I was setting it up, turned itself off, ruining my first measurement. Don't know why there is no auto-on-off switch anymore on monitors.

Note that there is no RCA jack. For my listening tests I just used a TRS to RCA and it worked fine. The acoustic measurements were made by driving the XLR connection from the Klippel KA3 analyzer balanced output.

Temperature during the...

This is a review and detailed measurements of the Schiit Freya S balanced preamplifier. It was kindly loaned to me from a member who bought it used. The Freya S costs US $599 from the company plus shipping cost.

The design language is identical to other Schiit product although in the widescreen format looks more attractive:

The volume control is stepped attenuator and you hear the chatter of the relays as you adjust them. A gain switch toggles between passive, active with "0 dB" gain and 14 dB of again. There is a mute button and input selector. A remote control is provided which I did not use.

There is good bit of connectivity is provided:

I performed all of my testing with balanced input, and balanced output.

I know this is like all other Schiit products but sure would be nice in this case to have a power button in the front, than in the back. I do turn my pre-amp on and off and...

This is a review and detailed measurements of the Meizu Hifi USB-C, smartphone DAC and Headphone adapter. I can't find a price on it but seems to be listed for US $35. it is on kind loan from an overseas member.

You can't see it in this picture but there is a cool circle showing what is inside of it:


As long as you have a headphone plugged into it, Windows 10 automatically installs the driver for it. And works down to 24 bits with no issue.

My new custom PC has a USB-C native port on it and that is how I tested. But I also tested it with the USB hub in my monitor which I used to use for much of my DAC testing. See a comparison of that below.

Headphone DAC & Amp Audio Measurements
As usual we start with our dashboard view:



There is a lot of good news here starting with 2 volt output instead of the typical 1 volt and very low distortion. Not so good news is that noise level must be high to...

This is a review and detailed measurements of the Revel C52 center, three-way speaker. I purchased it years ago for my theater. It comes in a gorgeous maple finish which Harman was discontinuing so I got them for a song. It costs US $2,499. It has been on the market for well over ten years, if not fifteen.

My photo booth is too small for the speaker. So here is a quick shot of it as it sits in the Klippel NFS measurement system in our messy garage:

It is quite heavy for its size and took effort to lift it to put on the platform. This is a cell phone picture and is a shame you can't see the quality of the finish.

Here is the back side:


Those bus bars connecting the tweeter to woofer/mid-range section are so shiny and high quality you want to wear them as jewelry! I kid you not.

You can see the test conditions with "stand mounted" selected and tweeter level set to 0 dB...

This is a review and detailed measurements of the minidsp U-DIO8 8-channel USB to and from AES/EBU digital converter. It is kindly sent in by a member. The U-DIO8 costs US $325 from the company. It is a very cool device in that it lets you stream 8 channels of audio to multiple independent devices. Or capture data form them in reverse. There is also a S/PDIF version.

The box is small which is a bit of a drawback as they used a 25-pin DB connector with a thick dongle to get the inputs and outs:


The connectors feel a bit cheap and I had a hard time inserting and removing my XLR cables from them. Not a big deal though in operation.

You need a 5 volt input adapter which I did not get. So I tested it using my lab power supply.

Digital Audio Measurements
I have been struggling to get good template for measuring digital output devices and I think I have finally found it. I play the J-test signal (12 kHz @ 48 kHz sampling)...

This is the measurements of the March Audio P502 class D amplifier based on Hypex (?) modules. It was kindly send to me by a member for testing. The P502 costs US $1,075 from the company direct.

This is not a review because the @March Audio is a long time member of the forum and I like to avoid conflict of interest.

The unit comes in attractive aluminum packaging:

On off control is a touch button which is unusual in power amplifiers.

Here is a shot of the back:


In hard use, the bottom plate gets quite warm. Make sure you have plenty of ventilation from below. A taller set of feet would help with this.

My heavy stress test of frequency versus power caused the unit to shut down momentarily. I did not retry it as I don't want to risk damaging the unit.

Warm Up Test
As is my standard practice now, I warm up and measure distortion and noise until the device...

This is a review and detailed measurements of the Kali Audio IN-8, 3-way powered studio monitor (speaker). It was kindly purchased new by a member and drop shipped to me. The IN-8 costs US $399 each.

Despite its rather low price, the IN-8 comes in a rather large enclosure and with good visual fit and finish:

The tweeter is located in the center of the midrange driver ("coaxial").

Here is the back panel connectivity and EQ settings:


I tested the unit as shipped with all the dip switches low (EQ defeated). For listening tests, I used the RCA input so had to enable that using dip switch 8. Gain control was set to middle (0 dB) as you see. I think the drive level was 0.7 volts through XLR input. I used a microphone position that was a bit farther away from the speaker. To compensate, I had to boost the levels. They were somewhat uncomfortable to listen to from 6 to 7 feet away. I...

This is a review and detailed measurements of the Sunfire HRSIW8 DSP Subwoofer Class D amplifier. It is on kind loan from a member. The HRSIW8 seems to have come out back in 2012 with its companion in-wall subwoofer. As best as I can tell, the retail price is US $999 but I see it on ebay for much less.

HRSIW8 comes in a compact, 1-U configuration:


It is extremely heavy for its compact size. Hefty relays click on and off when you power the unit. A rotary control changes the volume. Press it and you get into a number of menus. Alas, there is no parametric EQ is available which would be highly useful to get rid of room modes. Instead you have a crossover and different modes for "music," etc. The crossover is fully programmable as far as frequency and roll off steepness. I set the crossover frequency to highest it would go (160 Hz) for testing.

Note that this is a single channel of amplification.

Subwoofer Amplifier Audio...

This is a review and detailed measurements of my NHT Pro M-00 powered studio monitor (speaker). I purchased it probably 15 years ago upon a hugely positive review from stereophile(?). It said some famous recording engineer used to mix a ton of popular albums. I bought the package with the S-00 subwoofer. Each speaker cost $249 and the sub was $500 for a total of $1,000.

Years later, NHT hit hard times and closed shop for a while. Then went online direct. I have not kept track of what they do now. These speakers are no longer available but as part of our effort to build up some "speaker measuring muscle," I thought it would make for a good second review. Be sure to read my first review of JBL 305P Mark ii to understand this data better.

The M-00 is a small but weighs like it is filled with rocks:


The case is...

This is a review and detailed measurements of my Mark Levinson No. 360S DAC. I purchased it sometime around 1999 when the new high resolution formats had come out (DVD-A and SACD). It has been a solid foundation of countless audio evaluations I have performed near two decades now. The 360S was the hand tuned version of 360. I think that made it cost $2000 more? I forget how much it cost but probably around $7,000. In today's dollars, that would be well over $10,000. So not cheap. Used ones seem to go for as much as US $3,000.

This thing weighs a ton for a DAC and that is the reason I hate you all for asking me to rip it out of my cabinet to test it!


Lots of connectivity was provided but alas, no USB, HDMI, etc.:


The brochure talked at length about modular architecture that would allow addition of new input types. Well, no. Nothing of the kind ever arrived. As such, to use it in...

This is a review and detailed measurements of the HIDIZS S8 USB-C DAC and Headphone Amplifier. It was kindly sent to me by the company. It is a new product and I don't see it broadly advertised. I only found one site selling it for US $129. So quite high for a dongle.

The box is much larger than the unit itself which weighs next to nothing:

Three different adapter cables are provided to mate it to USB-C, Apple Lightning and straight-through so should work with any phone.

The up down buttons work well.

I tested the S8 on Windows 10 which recognized it properly (you have to plug-in the headphone first). Alas, the ASIO4ALL interface I use to test audio products with my analyzer truncated 24 bit samples to 16 bit as it sometimes does. For this reason, I had to run a number of tests manually and a few I had to leave out. But I think you will get a good picture of its performance as is.

FYI, the company contacted me after I reviewed...

This is a review and detailed measurements of the JBL 305P Mark ii powered studio monitor and Control 1 Pro budget passive monitor. I purchased the 305P Pro Mark ii when it first came out and it currently sells for US $147.50 from Amazon including Prime shipping. This is the price for one so you need to double that for stereo setup. The Control 1 Pro came with my Klippel NFS speaker measurement system. It is only sold through Pro channel and costs US $164 for a pair.

The 305P Mark ii has good heft and feel to it for a budget priced monitor:

Back panel shows the connectivity and configuration:

The Control 1 Pro doesn't feel like junk but not anywhere close to 305P:


Introduction
This being the first...

This is a review and detailed measurements of the "travagans tài píng tiān guó DC Filter." It is from a company in Taiwan and the only mention of it is in a couple of facebook posts. A member kindly sent it to me for review. I have no idea how much it costs.

The Travagans filter comes in a poorly made Baltic Birch plywood:


Oddly, there is a voltmeter inside it which shines through the top if you squint enough:


It shows the voltage to two decimal places. I am sure there are people at Apple who are having a heart attack that someone has mastered industrial design and usability better than them!

Anyway, the...

This is a review and detailed measurements of the ifi DC iPurifier DC (power) filter. It is on kind loan from a member. The iPurifier costs US $99. Looks like there is an updated, iPurifier2 now.

The ifPurifier is an inline DC filter. Power goes in, power goes out. I received a set of adapters with it, not sure if these come with it or not. If not, you definitely need it as these barrel connectors come in a few sizes of outside diameter and inside.

The unit itself is a bit chunky so may not mate with some devices:


The challenge with these devices is not that they don't do anything. They do. The issue is if that change materializes in sound you hear.

Audio Measurements
For testing I thought we rely on USB power. "Everyone knows" that USB power is "dirty" so surely this is a perfect input to iPurifier to clean up. I used my Topping D50s as the target DAC since it has independent power that can be provided from USB...