Articles, Reviews and Measurements of Audio Products
Review and Measurements of Monoprice Portable Amp and DAC with THX
This is a review and detailed measurements of Monoprice Portable Headphone amplifier and DAC with "THX AAA" technology. I purchased this earlier in the week for USD $279.99. With tax it came to little over $300.
For those of you who don't know, THX has come up with amplification module with feed forward error correction which serves to lower distortion in amplifiers. My review of Massdrop THX Headphone Amplifier showed it to have exceptional performance, far and above anything I have measured before. So excitement has been built up for the same technology (but not identical part) used in Monoprice version. Here, we are treated to a portable headphone amplifier and DAC all in one.
The Monoprice Monolith THX has a very serious, business-line appearance:
It is similar to a modern smartphone but much thicker and...
For those of you who don't know, THX has come up with amplification module with feed forward error correction which serves to lower distortion in amplifiers. My review of Massdrop THX Headphone Amplifier showed it to have exceptional performance, far and above anything I have measured before. So excitement has been built up for the same technology (but not identical part) used in Monoprice version. Here, we are treated to a portable headphone amplifier and DAC all in one.
The Monoprice Monolith THX has a very serious, business-line appearance:
It is similar to a modern smartphone but much thicker and...
Review and Measurements of Audio-gd NFB28.28 DAC and Headphone Amp
This is a review and detailed measurements of Audio-gd NFB-28.28 DAC, headphone amplifier and pre-amplifier. It is on a kind loan from a member and retails for USD $750 plus shipping from China. The unit is quite heavy so I suspect shipping will cost a few dollars.
This is a deep enclosure but half the width of the larger Audio-gd products:
Navigating the unit is maddening. 7-segment LED digits are used to indicate input number, setting, etc. I searched for the manual but could not find any. Instead there is some random text on Audio-gd website that starts to deal with something about a problem they fixed. How a simple device is made so complicated is beyond me. The unit could stand serious cleaning up of the documentation and revamping of the user interface.
There are lots and lots of inputs and outputs. I let you read the documentation for yourself. For my testing I used the USB input and either balanced XLR output for DAC...
This is a deep enclosure but half the width of the larger Audio-gd products:
Navigating the unit is maddening. 7-segment LED digits are used to indicate input number, setting, etc. I searched for the manual but could not find any. Instead there is some random text on Audio-gd website that starts to deal with something about a problem they fixed. How a simple device is made so complicated is beyond me. The unit could stand serious cleaning up of the documentation and revamping of the user interface.
There are lots and lots of inputs and outputs. I let you read the documentation for yourself. For my testing I used the USB input and either balanced XLR output for DAC...
Review and Measurements of Chord Mojo DAC and Amp
This is a review and detailed measurements of Chord Mojo portable DAC and headphone amplifier. It is on a kind loan from a member. Retail price is USD $599 but I see Amazon showing it for $532 including prime shipping.
The Mojo is a small but chunky and heavy as portable headphone amplifiers go:
The case feels like it is filled with lead and you could run a car on top of it and have it escape unscathed.
Let me get out of the way that I am not a fan of its whimsical look. But much worse is forcing a human to decode hues and color intensity of lights to detect what mode the unit is in. Why oh why? For $600, I expect something more informative than what is offered here. I will for example happily take a rotary volume control over those two blue buttons for volume level.
The Chord products are popularized by its designer, Rob Watts who is quite active online, and in audio shows/conferences. Having technical designers mingle with social media...
The Mojo is a small but chunky and heavy as portable headphone amplifiers go:
The case feels like it is filled with lead and you could run a car on top of it and have it escape unscathed.
Let me get out of the way that I am not a fan of its whimsical look. But much worse is forcing a human to decode hues and color intensity of lights to detect what mode the unit is in. Why oh why? For $600, I expect something more informative than what is offered here. I will for example happily take a rotary volume control over those two blue buttons for volume level.
The Chord products are popularized by its designer, Rob Watts who is quite active online, and in audio shows/conferences. Having technical designers mingle with social media...
Review and Measurements of Denon AVR-4306
This is a review and detailed measurements of the amplifier section of the Denon AVR-4306. At the time of this writing, we are still searching for a high-performance amplifier at reasonable prices. None of the new gear purchased has achieved the right bar so I dug into my inventory of old audio products and found this Audio/Video receiver. I think I bought it 12 to 15 years ago. I see mentions of it as far back as 2005. So in audio terms, it is a grandpa. 
I see the AVR-4306 on Amazon from a number of sellers starting at $389. On ebay, I found $189 including free shipping.
As expected, these AVRs are huge as compared to desktop or even some pro products I have tested. The number of jacks seemingly is a marketing thing with more the merrier.
For my testing, I only focused on using the unit as a 2-channel amplifier and put it in "CD direct" mode. I also tested it in "pure" mode but made no difference.
Let's get into measurements and see if...
I see the AVR-4306 on Amazon from a number of sellers starting at $389. On ebay, I found $189 including free shipping.
As expected, these AVRs are huge as compared to desktop or even some pro products I have tested. The number of jacks seemingly is a marketing thing with more the merrier.
For my testing, I only focused on using the unit as a 2-channel amplifier and put it in "CD direct" mode. I also tested it in "pure" mode but made no difference.
Let's get into measurements and see if...
Review and Measurements of Behringer A500 Amplifier
This is a review and detailed measurements of the Behringer A500 "Reference" Power amplifier. I purchased this unit on suggestions from members from Amazon for just $199 including Prime shipping.
Being targeted at the pro market, this is rack-mount unit with heft heatsinks on each side:
Full compliment of inputs are provided from RCA to balanced XLR and TRS. No input selector is provided though and the manual warns against simultaneous connection to more than one input.
The plastic volume knobs feel cheap but otherwise, it seems to be a sturdy build.
The manual says it has a class AB output stage. I am assuming some kind of power rail voltage switching is used to keep power consumption generally low but I have not confirmed this.
For my testing, I used a 4 ohm dummy load and balanced XLR inputs. Let's get into measurements and see how she did.
EDIT: the first revision of this review had tested the A500 with the input...
Being targeted at the pro market, this is rack-mount unit with heft heatsinks on each side:
Full compliment of inputs are provided from RCA to balanced XLR and TRS. No input selector is provided though and the manual warns against simultaneous connection to more than one input.
The plastic volume knobs feel cheap but otherwise, it seems to be a sturdy build.
The manual says it has a class AB output stage. I am assuming some kind of power rail voltage switching is used to keep power consumption generally low but I have not confirmed this.
For my testing, I used a 4 ohm dummy load and balanced XLR inputs. Let's get into measurements and see how she did.
EDIT: the first revision of this review had tested the A500 with the input...
Review and Measurements of NuForce STA-200 Power Amp
This is a review and detailed measurements of Optoma/NuForce STA-200 Power Amplifier. It is on kind loan from a member. I see it listed for USD $499 including Prime shipping. Looking elsewhere, it appears to have a list price of $1299.
This is one attractive enclosure that does not usually come in a $500 package:
The finish is slightly textured and looks pretty nice.
Feature wise, there is nothing there but a set of RCA inputs and speakers. The RCA inputs are paired with speaker terminals on each end of the unit so you better have RCA cables that separate that much.
Somewhat out of character is a traditional extruded aluminum heatsink poking out the back. I guess this avoids having to put the heatsink inside and having to vent the enclosure. The heatsink is pretty small though and it was cooking even when testing the unit at just 5 watts/channel. I worry about its ability to run OK at full power for any extended amount of...
This is one attractive enclosure that does not usually come in a $500 package:
The finish is slightly textured and looks pretty nice.
Feature wise, there is nothing there but a set of RCA inputs and speakers. The RCA inputs are paired with speaker terminals on each end of the unit so you better have RCA cables that separate that much.
Somewhat out of character is a traditional extruded aluminum heatsink poking out the back. I guess this avoids having to put the heatsink inside and having to vent the enclosure. The heatsink is pretty small though and it was cooking even when testing the unit at just 5 watts/channel. I worry about its ability to run OK at full power for any extended amount of...
Review and Measurements of Topping TP60 and FX Audio FX502SPro Amps
This is a review, measurement and comparison of two speaker amplifiers: Topping TP60 and FX Audio FX502SPro. I purchased both personally. The TP60 retails for USD $199 with free prime shipping but goes on sale frequently on Massdrop where I purchased it for just $135. I bought the FX502SPro for $68 from ebay but I see it listed at $89 right now.
From build quality to size and weight, the Topping TP60 blows away the FX Audio FX502SPro as you see in this picture on my bench:
The TP60 is probably four times larger. Part of that is due to the fact that it has dual linear power supplies built into it. The FX502SPro on the other hand, comes with a large laptop sized external switching supply that is nearly its own size!
The TP60 has dual inputs whereas the FX502SPro only has one. Rear speaker terminals on the FX502SPro are toy sized whereas the TP60's are much more substantial.
FX Audio rates the FX502SPro at 70 watts per channel...
From build quality to size and weight, the Topping TP60 blows away the FX Audio FX502SPro as you see in this picture on my bench:
The TP60 is probably four times larger. Part of that is due to the fact that it has dual linear power supplies built into it. The FX502SPro on the other hand, comes with a large laptop sized external switching supply that is nearly its own size!
The TP60 has dual inputs whereas the FX502SPro only has one. Rear speaker terminals on the FX502SPro are toy sized whereas the TP60's are much more substantial.
FX Audio rates the FX502SPro at 70 watts per channel...
Review and Measurements of Massdrop THX AAA 789 Amp
This is a review and detailed measurements of the just Massdrop THX AAA 789 headphone amplifier. It was drop shipped by request of a kind member for testing. It retails for USD $349.99. The unit had a log gestation period with customers having to wait months to receive the first allotment. The second drop had a ship date of February so if you have not gotten in line, you will be waiting a long time for one. Is the wait worth it? Let's find out.
On the industrial design, Massdrop is using their current design language for their larger desktop audio products which in my opinion is a good thing. While the unit does not have a luxury feel to it, it looks serious and not cheap:
Very conveniently, there are three headphone jacks in front: 4-pin XLR for balanced headphones, and both 3.5 mm and 1/4 inch for single ended. As usual, please note that the word "balanced" here simply means more potential power, and has nothing to do with...
On the industrial design, Massdrop is using their current design language for their larger desktop audio products which in my opinion is a good thing. While the unit does not have a luxury feel to it, it looks serious and not cheap:
Very conveniently, there are three headphone jacks in front: 4-pin XLR for balanced headphones, and both 3.5 mm and 1/4 inch for single ended. As usual, please note that the word "balanced" here simply means more potential power, and has nothing to do with...
Review and Measurements of Topping DX3Pro DAC and Headphone Amp
This is a review and detailed measurements of the brand new, Topping DX3Pro DAC and headphone amplifier. The company kindly sent me a pre-production unit. I usually buy my Topping products unless they are not available in the market as was the case here. The retail price will be $219.99. I expect production to start soon given the high finish of the unit I have.
It is hard to fall in love with budget desktop audio products but there are exceptions and this is one of them. The Topping DX3Pro is darn cute!
The yellow LED as with the Topping D10 adds a much needed touch of color and uniqueness to the unit. The volume knob adds more to that sauce, making for a small box and you enjoy glancing at on your desk.
Surprising for a small unit, as seen in the picture, you get a remote control and all the functionality in its larger brother, the Topping DX7s. You can select the volume control to apply to line out, headphone out or both...
It is hard to fall in love with budget desktop audio products but there are exceptions and this is one of them. The Topping DX3Pro is darn cute!
The yellow LED as with the Topping D10 adds a much needed touch of color and uniqueness to the unit. The volume knob adds more to that sauce, making for a small box and you enjoy glancing at on your desk.
Surprising for a small unit, as seen in the picture, you get a remote control and all the functionality in its larger brother, the Topping DX7s. You can select the volume control to apply to line out, headphone out or both...