SMSL B2 Bluetooth/USB DAC Decoder Review

I have a few SMSL products already in my setup (a long term review of the SMSL SU1 DAC and SMSL D6S will be out in a few weeks) and these devices always impress me with their understated technical brilliance. Having used the SMSL B2 for a month or so I now have the same feeling about the SMSL B2, there is no way a device with this audio quality, and features it provides should be availalbe for $79.99.

Introduction

The SMSL B2 Bluetooth/USB DAC Decoder is a bluetooth receiver and Usb DAC that is designed to easily provide bluetooth capability to an existing stack but would also work well in a desktop setup as a USB DAC.

For a tiny device it offers some very nice features and I would like to share my findings in this review, read on to find out what you can expect.

Unboxing and build quality

The SMSL B2 arrives in a neatly packed box:

Inside we get:

• SMSL B2 DAC Decoder
• USB cable
• User manual and SMSL ‘registration’ card
• Bluetooth Aerial

The packaging is simple yet efficient, ensuring all components are secure.

Make sure to take off the protective film on the screen:

The SMSL B2 is tiny, here is its size compared to the already tiny SMSL SU-1:

Features

Connectivity

The SMSL B2 offers multiple input and output options, enhancing its versatility:

• Inputs: Bluetooth and USB
• Outputs: Optical, Coaxial, and RCA

This range of connectivity options allows the B2 to be integrated into various audio setups, from desktop speakers to home theater systems.

Bluetooth Capabilities

Equipped with Bluetooth 5.1, the SMSL B2 supports several high-quality codecs:

• LDAC: 24bit/96kHz (990kbps/660kbps/330kbps)
• aptX-HD: 24bit/48kHz (576kbps)
• aptX: 16bit/44.1kHz (352kbps)
• SBC: 16bit/44.1kHz (328kbps)
• AAC: 16bit/44.1kHz (320kbps)

These codecs ensure high-fidelity wireless audio streaming, accommodating a variety of devices and audio sources.

Display

The B2 has a gorgeous little display which is realitively large especially compared to the size of the B2:

When listening to bluetooth as you can see above, as well as the connectivity details and sample rate you get nice details about the audio track playing. I loved this capability it adds something to your listening when you can see the track information without having to look at your phone.

But when using the B2 as a USB DAC you will only get the connectivity details and sample bit rate.

USB Specifications

The USB input supports asynchronous transfer, ensuring precise and jitter-free audio transmission. Compatible with Windows 7/8/8.1/10/11 (driver needed), Mac OSX 10.6+, and Linux (driverless), the B2 offers broad compatibility across different operating systems. The USB input also supports a 24bit/44.1kHz or 48kHz sampling rate, maintaining high-resolution audio playback.

Performance Metrics

The SMSL B2 boasts impressive audio performance metrics:

• THD+N: 0.0002% (113dB)
  • At 0.0002%, the B2 provides exceptionally low distortion, ensuring that the output audio is nearly identical to the input signal, free from unwanted harmonic distortion and noise.
• Dynamic Range: 128dB
  • A dynamic range of 128dB means the B2 can handle a wide range of audio signals from the quietest to the loudest without losing detail, making it suitable for high-resolution audio playback.
• SNR: 128dB
  • With an SNR of 128dB, the B2 ensures that the audio signal is significantly stronger than any background noise, providing a clean and immersive listening experience.
• Output Level: 2Vrms
  • The output level of 2Vrms indicates that the B2 can deliver a strong and consistent signal to connected audio equipment, ensuring optimal performance and sound quality.

These specifications highlight the B2’s capability to deliver clear, detailed, and dynamic audio reproduction, making it suitable for critical listening.

Power Efficiency

With a power consumption of less than 1W and standby power consumption of less than 0.1W, the SMSL B2 is energy-efficient, making it an environmentally friendly choice.

Measurements

SMSL have provided Audio Precision measurements of the B2’s performance :

In this price range this is an excellent SINAD / THD+N score and even a few years ago would be asstonishing. Basically this means the B2 is a transparent DAC via USB. You should not worry about this DAC adding any noise to the output even if you need to use say a digital EQ later in your audio chain (for example EQ can use up maybe 10Db of ‘gain’ but even ’taking 10db from 114Db that would be well beyond the limits of human hearing which can be arguable between 70dB and 80dB).

Bluetooth is slightly worse but still absolutely perfect from a subjective audio perspective and I can confirm these figures in my measurements - see below.

Digital output - effectively using the B2 to feed Optical or Coaxial output into an existing DAC provides excellent performance.

What I like about have digitial outputs on the B2 is, you can start with the SMSL-B2 and then maybe you want to upgrade the DAC but you sill want to keep the bluetooth our USB inputs than you can digitually feed the B2 into another probably more expensive DAC and happily that connection will not introduce any noise into the audio chain.

My own measurements

Using my Cosmos ADCiso, I also measured the B2 Frequency and distortion and found it to be inline with these published measurements.

Firstly the Frequency response and distortion accross all frequncies: As you see the Frquency response is flat until about 17K+/18k+ when there is roll off. There is very little audible “information” at this frequncy and as we get older you wont be able to hear those higher frequencies but it is worth mentioning and possible a reason to ultimately feed the B2 output into an external DAC (if you are still in your 20’s and can hear those higher frequencies).

The Distortion in this greph shows that it is well controlled accross all frequencies. Some vendors have been ‘accused’ of distortion the SINAD / THD+N measurements (which only measure THD at 1000Hz ) but as you can see other than a slight increase in sub-bass the THD values are well controlled accross the entire audible range.

Finally I thougth showing the distortion as a % might be useful: This again shows that the distortion is well controlled and other than the 2nd harmonic being slightly higher contributes to this being only a ‘good DAC’ from being an exceptional DAC at any price range. But it is still shows exceptional performance for a DAC at $79.

Sound Quality

For those who like subjective sound quality - I was listening to the B2 for about a week using my Macbook Pro USB output (with the Mac Audio set for high-res Audio 96Khz / 24bit) and streaming AAC from my iPhone and LDAC from my Android based FiiO DAP.

Bass

The SMSL B2 delivers a tight and well-controlled bass response. The low frequencies are punchy and precise, providing a solid foundation without overpowering the rest of the audio spectrum. This makes it suitable for a variety of genres, from electronic music to classical.

Midrange

Midrange frequencies are handled with exceptional clarity and detail. Vocals and instruments are rendered with accuracy, allowing for an engaging and realistic listening experience. The B2 excels in reproducing the subtle nuances that bring music to life.

Treble

Fpr me the high frequencies are crisp and clear, extending without harshness. The treble response adds a sense of air and openness to the audio, enhancing the overall listening experience. The detailed treble ensures that high-frequency sounds are reproduced with precision. As you can see from the measurements, if you are still in your early twenties you might discern a little treble roll-off but for me as someone whose hearing does trail off below 18K I could not near anything missing between the B2 and my other DACs.

Soundstage and Imaging

The SMSL B2 offers a wide and immersive soundstage, allowing listeners to perceive the spatial arrangement of instruments and vocals accurately. Imaging is precise, providing a realistic and three-dimensional audio experience. This enhances the enjoyment of complex musical compositions and high-quality recordings.

Rating

Considering its impressive performance, versatile connectivity, and excellent sound quality, the SMSL B2 Bluetooth/USB DAC Decoder earns a pragmatic rating of 5 stars. For its price it is hard to beat, it is basically a 2 in 1 device, even if you are not that interested in bluetooth “streaming”, its USB dac capability combined with its very nice screen are worth the price. If you are ‘chasing measurements’ or like tweaking DAC filters with a remote control then you will need to spend more money but for $79.99 this is a great device.

Conclusion

In conclusion, the SMSL B2 DAC with Bluetooth and its Cirrus Logic chipset built-in is an exceptional product that caters to both audiophiles and casual listeners. Its combination of superior sound quality, good connectivity options, and user-friendly features make it a standout choice in the competitive DAC market. Whether you are looking to upgrade your desktop audio setup or seek a good-quality DAC for your home audio system, the SMSL B2 is a compelling option that delivers excellent performance with a very pragmatic price tag.