Articles, Reviews and Measurements of Audio Products

Yes, you read it right: I now own a second and the latest state-of-the-art analyzer from Audio Precision, the APx555. She is sitting here next to her elder unit to the left I have been using until now:



Avid readers know that I have been getting a lot of mileage out of my much older AP2522 unit. Despite being nearly 20 years old, it has had excellent performance. Great analog design and power of signal processing had kept it relevant for such use even now.

Alas, a few reasons prompted me to buy the new unit. First and foremost is the fact that the software for the new model allows me to directly talk to computer audio products through ASIO interface. You may have seen my difficulty in using my older analyzer there when a DAC doesn't have USB input. With APx555, I am able to now drive those products over USB just as well as it can using S/PDIF, Toslink, and analog output out of the analyzer. This makes measurements now the same whether I use USB...

This is a review of the HIFIMAN EF2A tube DAC and headphone amplifier. It is on a kind loan from a forum member. The retail price is $169 USD but I see it on Amazon for $139 plus shipping. I seem to recall it going on massdrop also. This is a small unit as you can see here, dwarfed not by one but two Audio Precision analyzers;



Typical of these "hybrid" headphone amplifiers, the tube is used as the input stage and the output drive is transistors. The see through lid shows a row of power transistors which hints at higher than normal output power.

I find the overall look cheesy and DIY type. The volume control though feels good. An external brick powers the unit.

Inputs are both digital in the form of USB and analog RCA. I tested the unit both ways.

Let's get into the measurements and see how she did. As usual, if you are not familiar with what these graphs mean, refer to my tutorial on understanding audio measurements...

This is a detailed review, measurements and comparison two portable DAC and headphone amplifiers: the Cypher Labs Theorem 720 and Fiio Q1 DAC. The Theorem 720 is on kind loan from a member. It is a circa 2013 product and quick look on third-party sellers on Amazon shows a retail price of $1,000. I own the Fiio Q1 and it retails for just $69 (plus $8 for shipping on Amazon). Obviously this is not an even match from price point of view but the Q1 was the only portable DAC+headphone amp I had that includes a battery like the Theorem.

Physically, the Fiio Q1 is quite a bit more slick and pocketable than the Theorem 720:


The Theorem 720 on the other hand looks like a hobby box. Definitely not for the pocket but portable nonetheless.

The Fiio Q1 does have a few faults of its own. Its volume control has no markings. The switch operation and LED lights are not easily decipherable from the poorly written manual.

Both products are...

This is a detailed review and measurements of the popular Schiit Modi 2 Uber DAC and comparison to Topping D30. I own both units. The Modi 2 Uber edition is one of the three versions of this DAC and retails for $149 plus shipping. The Topping D30 is available on Amazon Prime for $119 and includes shipping so good bit cheaper.



The two are similar in features in that both have three inputs: USB, S/PDIF coax and Toslink optical inputs. Both have external power bricks. The Topping has its power switch on the front which I prefer to the back switch of Modi 2 Uber. I also like the English labels on Topping as opposed to alien symbols used in Schiit Modi 2 Uber....

I recently performed a review of Schiit Fulla DAC and Headphone amplifier. This is a follow teardown of the unit.

Let's start with top down view of the unit:


Starting on the right side we see the typical USB controller (Cmedia CM6631A) driving an AKM AK4490EQ DAC. An external flash IC holds the firmware for the device....

This is a review and detailed measurements of KORG MR-2000S ADC and comparison to the ADC portion of RME ADI-2 ADC. I have previously measured the DAC portion of KORG MR-2000S and RME ADI-2 DAC.
The KORG has been on loan to me from a kind owner. It will be shipped back tomorrow so I won't be testing anything on it after the review. I own the RME ADI-2 Pro and will do more testing on it in the future.


The KORG MR-2000S is a stand-alone (and connected) professional audio recorder whereas the RME ADI-2 Pro is just ADC/DAC. So not in the same class of...

This is a follow up to my review of xDuoo TA-01 DAC and headphone amplifier. The TA-01 is powered by an external switchmode power supply:



Nearly a dozen screws hold the unit together. Once open, you are greeted with this:



Cleverly, it uses some kind of off-the-shelf DAC module vertically mounted...

This is a review and measurements of the XDuoo TA-01 tube DAC and headphone amplifier and comparison against Schiit Fulla (V2) solid-state DAC and headphone amplifier. Both are on loan to me from kind members although I had also purchased a Schiit Fulla V2. I may compare the two Schiit units later in light of some of the review outcome.



The XDuoo TA-01 retails for USD $160 on Amazon including Prime shipping. The Schiit Fulla is $99 from Schiit direct (not sold elsewhere) and you have to add shipping to it. So prices are not identical but close.

The XDuoo as you see in the above picture, resembles an aircraft instrument or something. It definitely has nice design cues. The volume is hefty and feels nice with that big knob. Toggle switch and power indicators are nicely in the front. It comes with an external switching power supply. It...

I measured the Focusrite Forte recording interface. In this case focusing on the DAC. This was a nice two channel recording interface which has been discontinued. The ADC and DAC chips and much of the circuitry is what is used in the current Focusrite Clarett line of interfaces. It has two microphone inputs with up to 75 db of gain which is higher than usual. Also line level and instrument inputs (for guitars). Headphone, and monitor outputs. It is a 24bit/192 khz ADC/DAC. The Forte has a Display Port dongle for some connections and a touchscreen for many of the controls. It connects via USB using ASIO in windows and Focusrite software in Mac. It sold for most of its life around the $450 to 400 mark.



The measurement FFTs are all 32K FFTs as is the custom on ASR. The spectrograms used a 2k FFT. As is Amir's custom I'll start with a 12 khz -1 db tone. Very...

In my https://audiosciencereview.com/foru...iew-and-measurements-of-topping-d10-dac.2470/, I was asked how well the D10 does as a USB to S/PDIF (and Toslink) converter since it has those outputs. I thought I make this review and measurement its own topic.

The Topping D10 is nice and tiny and no bigger than many USB to S/PDIF converters. What's more, it has a nice display which many lack, showing the sample rate:


At $75 including shipping (albeit on Massdrop), it is also price competitive with other such converters.

Let's get into measurements and see how it does.....