Articles, Reviews and Measurements of Audio Products

This is a review, listening tests, and detailed measurements of the Space II stereo headphone amplifier. It was sent to me by the Australian ASR member and designer, @SpaceAudio. Price is TBD: EDIT: Price is US $400.

I don't know what the case is made out of but it is extremely solid and dense. Would expect it to easily survive by driving on it! Simplicity is the name of the game here with a power button, volume and 1/4" headphone jack. The volume control feel is solid and satisfying. Back panel follows the simplicity road:


Space II Headphone Amp Measurements
Let's start with our usual "unity gain" 2 volts in/out dashboard:

I see no distortion products which...

This is a review and detailed measurements of the JBL MA7100HP 7.2/5.2.2 home theater AVR with support for 8K over HDMI. It was kindly drop shipped by a member and costs US $1,200.

The industrial design is absolutely stunning! JBL goes from mundane to top of the heap with a massive gap between it and #2! The front has sheet of glass (or is it plastic?) and is even lit with orange color that shines below. Unlike models below it, it has a large color display. It is easy to use but it does have some problem. The input control spins faster than the graphics can keep up. It is usable but either having a stiffer input selector or faster CPU response would have been nice. Volume level sadly is tiny as you see. There is plenty of space for it to be much, much larger.

Another annoying thing is that it applies processing to the inputs to convert to surround. You can defeat this but as soon as you power cycle it, it goes back to default! Many times...

Hello Everyone,

This is a review and detailed measurements of the Teac VRDS-20 stereo CD player.



I already mentioned multiple times that I’m into older CD players (like the Marantz CD-73), this is one more proof.

Teac VRDS-20 - Presentation

This CD player made me dream when I was much younger. It was way out of my league at the time.
It was released in 1993 at a very high price, featuring a unique look in the Teac range, with the 4 adjustable pillars at each corner. It was available in black and gold.

It plays only the initial silver disc, no SACD, no USB input, no, no Bluetooth either, sorry No digital inputs, too bad, Teac could have made an effort here.

The elements of interest are:

• The VRDS (Vibration-free Rigid Disc-clamping System) mechanism of course! This is the...

This is measurements of the HIRESFI AMPER502 Full Digital Amplifier. It was kindly sent by a member in EU and costs €116.16 (including tax).

As you see, this is clearly hobbyist level packaging. Inside though, it boast an ARM processor which is used to provide some level of signal processing. Alas, the equalization is at fixed frequencies so not very useful for speaker/room correction but can be used to do bass management and such. Core amplification is based on ST Micro STA350BW single chip "digital" amplifier IC.

Upon powering up the sample, the amplifier section turned off as soon as I pushed it above 3 watts (the processor was alive and well). It did that no matter if I drove one or both channels. It stayed up a bit longer with 8 ohm but still would shut down at 5 or so watts. Owner had it shut down also but when playing loud so had supplied me with a beefy 24 volt switching supply. I wanted to test with another but could not find a...

This is a review, detailed measurements and listening tests of Fosi Audio DS2 portable DAC and balanced headphone amplifier. It was sent to me by the company and costs US $55.

Well, it looks like a dongle. The LED seems to indicate the sample rates. What I like is inclusion of 4.4mm balanced drive and hard button volume controls:



Let's measure it and see where it stands.

Fosi Audio DS2 Measurements
Let's start with the balanced output:

Wow! I did not expect this level of performance! We are talking good desktop class DAC output here with SINAD that tops the chart of all portable devices I have ever tested:



Unbalanced output is naturally limited to 2 volts:

Even this performance is great with highest level distortion at -120 dB (below threshold of hearing).

Good news doesn't stop there...

This is a review and detailed measurements of the Topping B100 "monoblock" amplifier. It was sent to me by the company and costs US $299.

I was surprised by the desktop/low profile of the amplifier. I expected something a lot taller/chunkier especially since this is a class B amplifier and not class D. Power supply is of course external:

Nice to see balanced input, three gain settings and trigger input.

The front panel power button is touch sensitive. You have to learn to just touch and remove your finger for it to power on. When it goes into protection, you have to hold it until error codes disappear and then touch again for powering up.

A wish for a follow up version is a series of tall color LED bars going from left to right for visual enjoyment. Kind of like...

This is a review, listening tests, equalization and detailed measurements of the Bang & Olufsen Beosound Balance wireless speaker. It was kindly drop shipped by a member and costs US $3,299.

The Balance doesn't deviate much from the typical look of these speakers but does manage to feel/look luxurious. Importantly, it is substantially heavier than any other smart speaker I have tested, bringing hopes of higher playback volumes and bass response. I was pleased to find good connectivity including analog input which I used for measurements (does away with latency of wireless connection):

I do wish the ports were labeled however. The info is in the manual but that is also hard to read with every paragraph written in what seemed like a dozen different languages.

The design is complex as you can see from this picture...

This is a review and detailed measurements of the Denon DCD-SA1.



As I already wrote in my previous reviews, I like testing CD Players, especially older ones. This is one more proof. My firs review of the Onkyo C-733 here contains information about my measurements which I try to align with the AES standard. It means that, over time, you can compare the devices I reviewed.

This is my first review of an SACD player, but really my interest is into CD Players, so that’s an exception I made as I needed to know what SACD (and its DSD format) had to offer.

Denon DCD-SA1 - Presentation

Released in 2005, nearly 20 years ago, it was top of the line CD/SACD player at a staggering price (7’000€+ in Europe). This player is one of those “statements” from the big Japanese names, as they like to produce...

This is a review and detailed measurements of the Jerry Harvey / JH Audio custom made IEM. It was kindly donated to the forum by a member and cost starts at US $2,299.


The multidriver IEM feels quite substantial. I was pleasantly surprised in how well it fit my measurement artificial ear. Alas, my own ears were not so fortunate as I could not even get them to stay there let alone seal. So no listening tests for this review.

I am told these were "the" go-to custom IEM for live music until competition arrived in the last few years. The review sample was made for a band member.

If you look to the top left, you see a set of trim controls that are supposed to change the bass response. I tested that and what they call "bass" extends up to 1 kHz! Shame as I was hoping it would boost < 100 Hz. On the other hand, I needed the controls to equalize the left and right channels. Setting them...

This is a review and detailed measurements of the Cambridge CXA81 MKII integrated stereo amplifier with digital inputs (USB, Toslink, Coax) and Bluetooth. It was kindly drop shipped by a member and costs US $1,199.

There are no visible changes from the original CXA81 I tested. I *think* the same is true of rear panel features:

I am still not a fan of the overloaded input button that toggles between BT and USB depending on how many times you press it. Otherwise there is not a whole lot to complain about. Let's see how it measures relative to original.

Cambridge CXA81 MKII DAC Measurements
Inclusion of Pre-out enables us to test the performance of internal DAC so let's start with that dashboard with...