Articles, Reviews and Measurements of Audio Products

This is a review and detailed measurements of the D'Amore E660.5 5-channel automotive amplifier. It is on kind loan from a member and costs US $299.

The E660.5 seems well built and as you can see, is in a rather large enclosure. I suspect that will let it run cool. In testing it did not even get warm. Power terminals are designed well with angled hex screws that bite wires quite well.

Company designer used to be at Fostex and currently builds a line of test instruments for automotive amplifiers so I expect good performance.

Note that my instrumentation is limited to 2 channels and that is what I tested. Power source is a custom Lithium battery bank with 100 Ah capacity (instantaneous power of hundred of amps). I was charging the bank as I was testing the amp so you will see rising voltage notations in the testing (ranging from 13.4 to 13.8 volts).

Note 2: I thought the amp...

This is a review and detailed measurements of the (SMSL) VMV D2R stereo balanced USB DAC with Bluetooth. It was sent to me by the company and costs US $999.

The DAC is quite heavy for its size and has pretty stout construction. User interface is similar to other SMSL products. A higher-end metal remote is provided:

Alas, no coin cell battery was included so I used the front panel for configuration of the DAC.

The DAC design is different than many other in that it uses a DAC IC from Rohm (BD34301EKV) instead of the usual ESS and AKM. Let's see how it performs.

If you are new to DAC measurements, be sure to watch my tutorial video.

VMV D2R DAC Measurements
Let's start with balanced output and use the default -2 dB on the volume control which generates our nominal 4 volts:

Noise performance is excellent...

This is a review, listening tests, EQ and detailed measurements of the Hidizs MP145. It was sent to me by the company and costs US $150.

The immediate impression of the shells is one of jewelry with its machined aluminum case. As you see, the included cable has 4.4mm balanced connection even though it doesn't need that (plenty sensitive to work fine with 3.5 mm unbalanced). Included in the case are three tip variants and nozzles (latter not shown):

As is typical, medium size tips match my GRAS 45CA measurement artificial ears best. But for listening, I have to go one size larger. I started with balanced tips but then tried to measure with the other tips. I found the process of swapping tips very difficult. The nozzle is large and the tips barely fit it. Good news is that once you get them on there, they going to stay. With some other IEMs...

This is a review, listening tests, and detailed measurements of the Dan Clark E3 closed back headphone. It was sent to me by the company and costs US $1,999.

As you see, the E3 has quite large cups which makes fitment on your ears quite easy. I used the headphone for about 2 weeks with good comfort. Compared to the Stealth, I thought it felt a bit heavier. On the looks, I find it kind of simple compared to the complex geometry of Stealth/Expanse headphones.

Let's measure it to see how it responds.

Dan Clark E3 Headphone Measurement
I expect compliance with our target and that is exactly what we have:

Indeed, it seems to comply a bit...

This is a review and detailed measurements of the Marantz AV10 Audio/Video Processor (AVP). It is on kind loan from a member and costs US $7000.

My picture doesn't do justice to the nice look of the unit. It is a massive step up from past Marantz AV products. I am still not a fan of the port hole and little information it shows but at least it now blends in with the rest of the unit. This thing is extremely heavy for a processor as well. I had to double check that it did not have amplifiers in it! The user interface is high resolution and relatively easy to use. One nit was that even though I had the HDMI out to my monitor, it would not bring up the full setup if I had it on CD with Toslink input. It required an HDMI input to do that. Strange.

An attractive metal remote control is provided. Usually these metal ones are not ergonomic...

This is a review, listening tests, equalization and detailed measurements of the ZMF Caldera planar magnetic headphone. It is on kind loan from a member and costs US $3,500.

The Caldera is absolutely gorgeous to look at. It is lightweight and with its large cup, very comfortable to wear. Will have to find out from the owner which set of pads it came with.
EDIT: owner let me know that it has stock lambskin perforated pads.

The large cups allowed almost instant fit on my GRAS 45CA headphone measurement rig. I am always happy when that happens.

ZMF Caldera Headphone Measurement
As usual we start with the headphone frequency response measurement and comparison with our target:

OK, I get the flattish bass response but what is up with the three troughs...

This is a review and detailed measurements of the Sound Devices MixPre-3 II multichannel recorder and audio interface with headphone output. It is on kind loan from a member and costs US $895.

It is a cute, compact and rigid recorder. Gain control for Channel 2 has a stiffer feel which I imagine is designed to let you find it in the dark by feel. The LCD on the right is bright and touch sensitive. It is a bit small for comfortable manipulation but can be done. The user interface is a bit odd in that there is no scrolling and you have to learn to click on "..." to go to the next page. There are a myriad of inputs and a few outputs:



I dread testing this class of device as it takes hours to figure out how to do even simple things. The MixPre-3 was no exception. I installed its ASIO driver but it would keep complaining that it was not seeing it. Windows wouldn't recognize it either. Eventually found a...

Klark Teknik Air Link DW20T/DW20R Quick Review and Measurements

This is a quick review of the Klark Teknik Airlink DW20T/DW20R. This was purchased by me for wireless subwoofer use although it is intended for full range use. The unique feature of this system is that it has XLR balanced in/outputs. The combo runs about $200.


The transmitter is rated at handling up to 10 dBU (2.45V rms) and the receiver is rated at producing up to 15 dBU (4.36V rms). However this is at an advertised performance of 0.1% THD+N (60 dB SINAD)!

Official Specifications
Frequency response 20 Hz to 20 kHz (±1 dB)
THD + N (distortion) 0.1% @ 1 kHz
Signal-to-noise ratio >90 dB
Transmission frequency 2.406 - 2.475...

This is a review and measurements of the ROLLS HV6 passive volume control. It was kindly sent to me by a member and is discontinued. It cost $65 when it was sold.

The box is quite solid and the volume has a nice, fluid feel to it. Note that the XLR input is stereo and not for balanced connections.

ROLLS HV6 Headphone Volume Control Measurements
Let's feed the HV6 4 volts and see what it outputs into high impedance at max volume:

While there is some loss, noise and performance are essentially as good as the source (the audio analyzer). I adjusted the volume down and performance remained proportional.

As noted, input impedance is constant at around 520 ohm. Output impedance changes from that value down to 5 ohm. That obviously interacts with the impedance of the headphone. And that...

This is a review and detailed measurements of the Aiyima A07 Max stereo class D amplifier. It was sent to me by the company and sells for (I think) $85 with the included power supply:

I like the little design touches and the much heavier enclosure (made out of steel?). I really appreciate the larger and staggered speaker binding terminals:


As you see, the power supply is rated at 36 volts @ 6 amps. It has no branding though so not sure about the safety marks. There are vent holes underneath and during the testing, the case stayed quite cool.

Let's see how it measures. If you are unfamiliar with what is about to follow, please watch my video tutorial:

Aiyima A07 Max Measurements
As usual we start with our dashboard:
[ATTACH type="full" alt="AIYIMA A07 MAX stereo amplifier...