SilverStone Ensemble EB01-E USB DAC Review

By Aidan Moore

Manufacturer: SilverStone Technology Co., Ltd.
Product Name: Ensemble Series EB01-E
Model Number: SST-EB01S-E (Silver)
UPC: 844761010614
Price As Tested: $189.99 (Amazon)

Full Disclosure: The product sample used in this article has been provided by SilverStone.

The Silverstone EB01–E DAC is the companion product in both form and function to the SilverStone EB-03 headphone amplifier. Together, these two components make up the current SilverStone Ensemble Series audiophile grade audio components.

An external audio DAC is a computer peripheral that is aimed at an audiophile market with function of improving the PC audio quality. All modern PCs have an audio IC integral to the PC motherboard, so an external audio DAC is considered to be an upgrade to a PC system. However, there is an ongoing debate on just how good standard MP3 audio actually sounds when played at standard sampling rates, and higher quality audio formats such as FLAC exist to provide a higher quality sampling options. These formats require a high speed DAC and low noise audio for the best playback.

The EB01-E goes one step further than a high speed audio DAC by offering additional digital inputs for standalone digital to analog conversion from an optical or coaxial digital audio source.

In this article, Benchmark Reviews looks at the EB01-E USB DAC to determine if it is worth upgrading a basic PC audio DAC, and evaluates the EB01-E performance as a stand alone audio DAC.

The SilverStone EB01-E has the following features:

(From SilverStone Web site)

• High quality DAC with improved performance
• Classic SilverStone Ensemble exterior design
• Easy one touch button for USB, optical or coaxial input
• Support highest format of up to 24-bit/192kHz
• Utilizes premium XMOS XS1 TQ128 USB decoder for accurate sound reproduction
• Includes TI PCM1798 D/A converter for producing high quality analog signal
• Includes TI NE5532 OP amp for optimal analog output

(from SilverStone Web site)

Model No.	SST-EB01-EB (black) SST-EB01-ES (silver)
Color	Black or silver
Material	Aluminum & steel chassis
Input	Asynchronous USB, optical, coaxial
Output	RCA
Sampling resolution	16~24 Bit
SAMPLING RATE(FS)	32~ 192 kHz
USB Decoder	XMOS XS1 TQ128
D/A Converter	TI PCM1798
OP Amp	TI NE5532
Operating system support	Windows XP, 7, 8, MAC OS

An external audio DAC is a product that will primarily appeal to someone with a significant digital music collection and a desire to get the best possible audio performance from their collection. A serious gamer might also take a second look at a standalone audio DAC as a way to improve the audio in his game, although he will most likely opt for an external box with a microphone input.

The Silverstone EB01-E is a sleek metallic enclosure with no discernible features visible from the front, except for the two previously mentioned blue LEDs.

The EB01-E does not have an external power supply; it requires a USB connection to a PC or USB power supply for its primary power.

The rear of the unit provides access to all of the digital audio inputs and one pair of analog outputs. The choice of active input is made by pressing the small button labelled “SW” on the rear right of the unit. A set of three blue status LEDs are used to indicate which audio input is currently active. In a typical user setup, access to this switch and observation of the LEDs can only be performed by looking behind the unit, or rotating the entire box 180° with the connecting cables in tow. It is possible, however, to simply press the “SW” button while listening for the appropriate audio input to be output.

This is a digital input only box with no input provided for an analog audio source. In most cases, the listener will connect the audio output of the EB01-E directly to a stereo amplifier, or through the matching EB03 headphone amplifier.

The USB digital audio sent from a computer to the EB01-E will go through three internal signal processing blocks before being output to the destination device.

First, the USB audio data must be extracted from the USB frames and presented to the digital to analog converter with perfect timing. There are a number of methods to perform this extraction, but the most important objective is to prevent any interruption of the incoming audio data. The EB01–E uses the XMOS XS1 to decode the audio data asynchronously. Asynchronous extraction is considered to be the most reliable way to ensure that no audio data is corrupted due to small timing differences between the host PC and the USB destination.

The extracted data is then converted to an analog signal by the TI PCM1798 DAC chipset, which has excellent jitter tolerance to further reduce the possibility of timing errors.

The final audio output needs to be buffered and amplified for delivery to the destination. The op amps used in the EB01–E are the NE5532s, which have been the go-to choice for op-amps for over 35 years in professional and high end audio equipment.

The output impedance of the NE5532 op amps is less than 1 ohm, and they are rated to drive a 600 ohm load directly. SilverStone includes a RCA to mini adapter to allow headphones to be connected directly to the EB01-E audio output.

The EB01-E USB DAC was tested for noise and distortion using audio content with a range of sample rates and bit depths, including a 44.1 kHz sampled 1kHz tone as the input.

The 1 kHz digitally generated sine wave was used In order to measure the signal-to-noise ratio. By observing the frequency spectrum of this signal at the EB01-E analog output it is straight forward to determine the inherent noise and distortion.

The EB01-E was also tested with two pairs of headphones ranging in impedance from 32 ohms to 150 ohms directly at the analog output. Subjective listening tests consisted of a variety of acoustic and electronic material from an iTunes library using both the USB and optical digital inputs

• Audio comparison DAC: MBOX DAC (24 bits, 48kHz sampling)
• PC Platform: :Windows 8.1 PC 64 bit
• Audio Program: Adobe Audition CS6
• Low impedance headphones: BeyerDynamic T5p (32 ohms)
• High impedance headphones: Sennheiser PC350 (150 ohms)
• Audio Test Material 1: 1 kHz sine wave 24 bits, 44.1kHz
• Audio Test Material 2: iTunes AAC encoded
• Audio Test Material 3: 96kHz 24 bit WAV music audio file

The analog output of the EB01-E was connected to an ADC with a sample rate of 96 kHz and a sampling depth of 24 bits. The measured noise floor of the ADC was approximately -110 dB with the ADC input grounded.

A number of initial tests were run with EB01-E sample rates and bit depths ranging from 16 bit/44.1 kHz to 24 bits/192 kHz. It was observed that in all cases the EB01-E output noise floor did not drop below 100 dB, suggesting that the output analog noise floor was dominated by the output stage op amps noise.

The output of the EB01-E is shown below with a 1 kHz tone sampled at 44.1 kHz and 24 bits. This lower sample rate is shown to provide greater detail of the audio baseband.

One very good reason to include an outboard audio DAC in computer system is to reduce the amount of analog cables connecting the PC to the audio system.

For example, I was running approximately 8 feet of standard stereo cable pair from my computer’s analog output to the ADC used for these tests. The frequency response of this output with the same 1 kHz tone is shown below.

Although this measurement only shows the audio response of one arbitrary computer set up, the key point is that measurable and potentially audible noise is definitely introduced when analog audio is routed rather than digital audio.

Subjective Listening Tests

After using the EB01-E as my primary audio source for several weeks, I did not encounter any glitches or audio artifacts with the USB audio input. I tested a range of audio source material including 192 kHz 24-bit sampled audio, Blu-ray audio and the range of compressed music formats. The output noise floor of the EB01-E is below the typical listening threshold when played at normal volume.

It’s interesting to note that in carefully controlled experiments (SACD), test subjects listening to audio did not have great success distinguishing between audio encoded at 16 bits and 44.1 kHz and the higher sample rate and bit depth content. What this means is that in most cases the EB01-E can be enjoyed at a standard 16-bit and 44.1 kHz sampling rate without fear of missing something in the audio. However, for those listeners who demand the peace of mind provided by the highest audio sampling rates, the EB01–E is more than capable of delivering the content.

A pair of headphones was connected directly to the audio output of the EB01-E using the included headphone adapter, and a wide range of audio material.was played using all three digital inputs.The volume was controlled on the PC, and the resulting audio was surprisingly good considering the lack of a dedicated headphone amplifier. This is a workable use case for the EB01-E, however the lack of a physical volume control within quick reach could result in a few loud jolts when listening to music.

In fact, care should be taken when switching digital audio sources with the rear SW button. You really have no way of knowing for sure what the source volume is, and it’s entirely possible to switch to an uncontrolled and unexpected high volume level. For this reason, caution is recommended when switching audio sources using the SW button when headphones are directly connected.

There are a number of scenarios where having a dedicated USB DAC with the capability to output a very high sampling rate and bit depth would be advantageous. If your computer is connected to an AV receiver for use with a home theater, then having the highest possible audio quality is a justified expense. Similarly, if you dock your laptop to a system which includes access to a larger audio system, then using a dedicated outboard audio DAC will definitely improve the audio quality from the laptop.

However, it’s really not essential to use the highest audio settings on the EB01–E in order to take advantage of its features. High sampling rates take up a considerable amount of USB bandwidth, which may be needed for other USB peripherals, and there is the question of whether all that extra sampling and bit depth can actually be heard.

To use the old car analogy, the EB01–E has more horsepower than you probably need, but just knowing it’s there might be worth the purchase price.

The Silverstone EB01–E has all the features that would be expected of an external audio DAC, and includes a few bonus extras. The ability to switch between digital audio sources directly on the unit, and the inclusion of a headphone adapter add to the overall value of the EB01–E package.

The EB01–E enclosure is part of the SilverStone Ensemble series of audio peripheral designs with a attractive and sleek brushed metal finish. It is obviously designed to be placed comfortably underneath the companion EB03 headphone amplifier.

As of April 14th the SilverStone EB01-E sells online for $189.99 (Amazon). I feel that the EB01-E delivers good value for the price. Most other outboard DACs do not include the standalone D/A conversion offered by the EB01-E.

The intelligent choice of high quality audio ICs in the EB01-E design is clearly highlighted in the documentation, and these design choices result in exceptionally good output audio performance.

+ Very good audio performance
+ Attractive design
+ Multiple digital source selection
+ Included headphone adapter
+ Low output impedance for headphone use

– Switching inputs is awkward
– Potential for unexpected loud audio when switching inputs
-No analog audio input

• Performance: 9.00
• Appearance: 8.50
• Construction: 9.00
• Functionality: 9.5
• Value: 8.50

Quality Recognition: Benchmark Reviews Silver Tachometer Award.