Articles, Reviews and Measurements of Audio Products

This is a brief review and measurements of miniDSP 2x4 HD Processor and USB DAC. I purchased this online and seems like the price as of this writing is USD $207 as of this writing. This is a USB DAC with Toslink optical input and analog/digital in, four channel digital signal processor (DSP).

The DSP features can be used to implement everything from active speaker crossovers to full room correction/equalization. While the former functionality is easy enough to implement, the latter is up to you to program. This is a "raw" platform with no intelligence of its own. If you want room equalization, you have to figure out how to program its individual parametric filters or FIR parameters.

The unit comes in a shiny aluminum case that feels decent and has just enough weight to not get dragged too badly by the myriad of connections you would have to hang from it...

This is a review and measurement of the Schiit Fulla DAC and headphone amplifier. It is the version 1 and is on kind loan from a member. If you are interested in V2/current version, I have purchased that, and the review will be forthcoming.

The Version 1 is a diminutive unit, a bit larger than the typical "thumb drive" sized USB DACs. It is made from folded metal like the larger Schiit products.

There are some sharp corners especially around the volume control knob that I wished were rolled off. Speaking of the volume control, it has rather low level of travel but it works and is convenient to have.

Format wise, this is an older DAC so limited to 96 kHz sampling rate as reported by Roon:



Yes, the USB identifier indeed says "I'm Fulla Schiit." Would be quite funny if the performance is great. Let's see if that is so in our measurements. If you are not familiar with my tests, I suggest reading my...

This is a digest of the Audio Engineering Society (AES) conference paper titled, “Distortions in Audio Op-Amps and Their Effect on Listener Perception of Character and Quality.” (http://www.aes.org/e-lib/browse.cfm?elib=16029) As the name indicates, it is a controlled listening test to see if there is audible difference between Op-amps (integrated small amplifiers) when operated below their clipping point.

In recent years, it has become quite fashionable to talk about what Op-amp are used in audio products or swap one for the other in the same vein. While subjective outcomes abound on efficacy of such differences, question becomes if there is any formal, controlled listening tests that can give us reliable indication of audible differences in Op-amps.

The paper in question aims to answer this question. It has good pedigree when it comes to its authors which includes the famous mastering engineer, George Massenburg, and other researchers from various...

This is a review and measurement of Intona USB Isolator. In the last few years there has been a proliferation of USB filters, cleaners, regenerators, feeding on fear of audiophiles of noisy computer ports. Intona doesn't actually play in that market directly. They built this device for industrial control applications where strict isolation from the machine being controlled is required. Audiophiles however, have been interested in the unit just as they are in other devices in this category.

This unit is on a kind loan from a forum member. It retails for USD $229 plus $29 shipping to US. It comes in a nondescript, plastic box. No pretense of being a audio jewelry here. For this review I compared the Intona to Uptone Regen and TotalDAC D1. You can see the full collection here:



Interestingly the Intona...

This is a review and detailed measurements of RME's new ADI-2 DAC. This is a spin off from their highly regarded ADC/DAC combo, the ADI-2 Pro. I have purchased the Pro for my testing but a member was kind enough to loan me the DAC only version reviewed here. I will measure and post any differences between the two at a later time.

The ADI-2 DAC retails for USD $999. The black version I received looks quite attractive with nice white LED highlights around controls and a high-resolution and highly responsive LCD display.


From a pure DAC functionality, it is better executed than my ADC/DAC. It has a remote control and unlike mine, has proper inputs for S/PDIF as opposed to a dongle.

The unit has huge number of settings and display material that is navigated through four switches and three rotary encoder, all of which are "clickable." Unfortunately this...

This is a review and (highly) detailed measurements of the Auralic Gemini 2000 DAC and headphone amplifier. It is on kind loan from a member who has been patiently waiting for its review! The Gemini is a lifestyle audio device, licensing the Klutz Design CanCan and embedding a DAC and headphone amplifier in its base:


The retail price is US $1,200. Seeing how Klutz charges $550 for its base alone, this is not an outrageous sum for a unit that adds the DAC and headphone functionality and with it, remove a lot of clutter from your desk.

Looking at the slick website and the picture of the PCB, I was salivating over its design:



This is a great use of white solder mask/silk screening of the PCB. You could literally eat off of the thing!

[...]

This is a "naked" review and measurements of the LH Labs Go2Pro DAC and headphone amplifier. I say naked because in in the interest of time, I am posting its results by itself. I am hoping by now you all are familiar with the norms in my measurements and can see its fidelity. Actually there is one measurement that includes a comparison.

I can't find its retail price but it is on sale now with 20% off at $480 on LH Labs website. So quite pricey. The unit is on kind loan from a member.

Anyway, this is a self-powered device (although I tested it while connected via USB) and includes a 3,200 mah battery. That combined with a metal enclosure makes for one hefty device.



I find the user interface maddening. There is a simple on/off switch but then the "up" volume control is overloaded as meaning both extra gain, and filter??? I confess I could not...

This is a review and detailed measurements and comparison of Massdrop Grace Design SDAC DAC. It is on kind loan from a forum member. The "drop" is over but when it was active, the unit costs $79. See it, and the detailed specs here: https://www.massdrop.com/buy/massdrop-x-grace-design-standard-dac.

The unit is similar size to JDS Labs OL DAC ($99 plus shipping) which I compared it to in this review:



Clearly they are after the same market and audience. While both have decent heft for what they are, they are both too light so support heavy cables and such.

The JDS OL DAC comes with an external linear power supply while the Grace SDAC is USB powered. The designer, Michael Grace, has written a nice post about the SDAC here: https://www.massdrop.com/buy/massdrop-x-grace-design-standard-dac/talk/1806625. Reading that, seems like good engineering...

This is a review and detailed measurements and comparison of Audio-gd NFB-27.38 DAC and headphone amplifier. It is on kind (and patient) loan from a forum member and ex-Microsoft colleague. The current website price is USD $1,688 plus shipping from China. There is no shopping cart which I assume it means you have to send money via Paypal and then wait for the unit to arrive from China. The loaned unit was purchased in China (?) and is an EU 240 unit powered by a transformer that converts 120 to 240.

The unit is massive by any definition of the word. It is the deepest piece of audio equipment I have seen let alone one for a DAC and headphone amplifier:



It can swallow four of the Topping DX7s' easily as the one on top of it right now shows. For that humongous size you get every possible input and output. I let you read all the specs for...

This is a teardown follow up to my review of Schiit Lyr Hybrid Tube Headphone Amplifier. The unit is on kind loan from a forum member.

Taking apart the Schiit Lyr, like their heavier units is a bit of a challenge as it uses an odd metal box inside another metal box. After taking out the outer box, you are greeted with the internal exoskeleton:



I could take this enclosure apart but that would require unscrewing the output transistors but since this unit is on loan, I chose to not do that.

Typical of most headphone amplifiers, the architecture is rather simple. To the left, covered by the box are a couple of transformers connected to AC mains (protected by a fuse). The output is rectified by a bridge rectifier and then filtered (cleaned) by the black electrolytic capacitors that are visible. They are made...