We have to admit that when we discovered the English hi-fi brand Graham Slee, we were a little curious at the sight of all these similar looking aluminium micro-cases. Specialized in phono pre-amplifiers, headphone amplifiers and smaller audiophile power supplies, Graham Slee uses the same casing to hold the several versions of its home made electronics. Not only are the Graham Slee products made in England, they are also home made, which explains their electronics’ slightly odd looks. Whoever purchases products from Graham Slee will not be getting the same hi-fi product as the average Joe… and will not be getting the same sound either.
The only USB DAC of the series
Graham Slee has only one model of USB DAC, namely the Bitzie, whose technical specifications will not thrill the aficionados of 192 kHz FLAC or DSD files, as the microchip used can, at best, read CD quality PCM files, 24 bits / 48 kHz at the most.
It is actually not that bad and you will see that this is not the most important factor.
The integrated digital to analog converter is a Texas Instruments model working in 24 bits and 192 kHz. Graham Slee deliberately chose to limit the compatible audio stream to 24 bits and 48 kHz.
It is true that we have a habit here at Son-Vidéo.com to praise studio quality digital sound. It is because when using quality electronics, this type of music provides a delightful fullness. Besides, USB DACs with an audio stream limited to CD quality able to provide real musicality are pretty rare. Yet, the Graham Slee Bitzie USB DAC is one of them. It is actually even more than this, as it crushes the competition within its price range and even beyond.
How is it connected’
Before conducting a test, let’s have a look at the device in its entirety. The Graham Slee Bitzie USB DAC is equipped with a type B USB port at the back as well as optical Toslink S/PDIF and RCA coaxial outputs. It is obviously made to be connected to a computer, be it a PC or a Mac.
On the front panel are 2 variable-level outputs, a 3.5 mm and a 6.35 mm jack. The latter, although using the same OP amplifiers is marked as line output. Graham Slee has included a gold plated jack to RCA adapter with its DAC so the Bitzie can be connected to an integrated amplifier or even to a power amplifier since the level is variable. Lastly, the volume knob can be found at the front of the device.
Why is the 24/192 microchip under-used’
Graham Slee noticed that too many DACs were overlooking CD quality audio files, while these are full of interesting details. The Burr-Brown converter is used in order to oversample PCM signals to obtain an analog conversion, which would not destroy high harmonic frequencies. The audio stream is treated in very high definition, even though it is CD quality.
Software configuration
Graham Slee offers no drivers for Windows or Mac OS, which is no surprise since this DAC is completely plug and play. Yet, be aware that a few adjustments will be necessary in order to get the best possible performances out of this device. We used the Bitzie with Windows and Foobar 2000, to which we added the optional Wasapi support. We decided to use the Event mode (see screenshot) in order to let the DAC manage the data extraction and streaming rate all by itself. This way, all the files were read with no alteration and very little jitter.
Hardware configuration
There will probably be an update of this review in the near future as we will be listening to the Graham Slee Bitzie with a pair of Hifiman HE-500 headphones then with a hi-fi amplifier and JBL speakers. For now, we have been using this DAC with our faithful Sennheiser PX100 headphones, which has been our reference set for many years. Although they might not be the best headphones out there, it certainly is a surprising and balanced model for its price.
First, we tested the Graham Slee Bitzie with an average USB cable, then with an Audioquest Carbon USB cable.
First impressions
Even without being broken-in, the Graham Slee Bitzie USB DAC is an immediate surprise due to its smoothness and analytic capacity. The vocals are remarkably delivered to the point that we feel like David Bowie, Janis Joplin, Thom Yorke or Sky Edwards are singing right in our ears. The Bitzie’s sound signature is absolutely analog, with a very pleasant high frequency range after only a few hours of breaking-in, a solid bass range and no over-the-top tricks.
Once this device is paired up with the quality USB cable it deserves you will immediately start a journey to a musical world you thought was reserved for vinyl. The DAC definitely benefits from the Audioquest Carbon USB (although it does cost about a third of the Bitzie’s price), the treble is extremely refined, especially when compared to an average USB cable.
The listening experience is enjoyable regardless of the song playing. The sound is delightfully rich and full.
A few tracks we listened to
For once we did not choose the usual reference recordings, leaving jazz and classical music aside to focus on rock and world music. To be honest, we looked for the most colourful tracks in our playlist to see if this little DAC could work with it and offer a convincing delivery. The answer is a resounding ‘yes’.
Don’t You, Simple Minds (FLAC 16/44)
The metallic sounding drums are remarkably well placed, so is the bass drum, the light guitar sound has room to breath, the synthesiser is aerial and the vocals benefit from a great echo.
Rapper’s Delight 12″, Sugar Hill Gang (FLAC 16/44)
How well articulated! The basic orchestration is delivered with an impressive fullness by the Bitzie. You don’t even have to be a fan to let yourself be carried by the raw sounding percussions and great bass line.
Knights of Cydonia / HAARP, Muse (FLAC 16/44)
Well versed people know that Wembley stadium’s sound recording is deafening and dry. The Bitzie adds the finesse the recording lacks in the high frequencies. The trumpets during the intro are of an impressive precision. Not even the slightest sign of harshness: just turn the level up and tap your foot.
Map of the problematique, Muse (FLAC, 16/44)
Another complex track with which it is often difficult to focus on Matthew Bellamy’s voice due to the intense mixing of the drums and guitar. Everything is coherent here. We end up tired, yet we had the feeling we just listened to the song the way it was supposed to be heard.
If you think Muse’s music is no more than a horrible amount of senseless noise for thrill seeking teenagers, the Bitzie will prove you wrong.
Me and Bobby Mc Gee, Janis Joplin (FLAC 16/44)
Completely different type of music, but equally difficult vocals. Janis Joplin’s harsh voice is full of emotions and changes constantly. The two piano tracks are easy to follow and so are the electric guitar and bass guitar. Joplin’s voice is a timeless delight.
Lo Chiamavano King, Juis Bacalov & Edda Dell’Orso (FLAC 16/44)
An old recording one can find on Django Unchained’s soundtrack, digitalised by Tarantino himself from his own record player. A two minute long mesmerizing ballad delivered in a completely comfortable way by the Bitzie.
Chambre avec vue, Henri Salvador (16/44)
Great coherence, the various layers of Henri Salvador?s vocals are remarkably clear. The trumpet is soft, the stand-up bass is full. The same goes for Jardin d’hiver: Salvador?s whistling voice is perfectly under control and never sounds harsh. A true work of art. 
Michel Telo, Ai se eu te pego (nossa nossa) (FLAC 16/44)
A song that has the ability to turn into a whistle festival due to the overly present treble in the mix. A mediocre conversion and your listening experience can turn into a nightmare. Fortunately, it is not the case with the Bitzie: the accordion finds its place, the drums provide a strong support with just enough echo. The crowd, mostly composed of women, sings loud and clear.
Original Sin, INXS (16/44)
Once more, a lot of echo here. Michael Hutchence rises above the supercharged music, bringing back moving memories.
All along The Watchtower, Jimmy Hendrix (16/44)
The tambourine sounds better than ever, clear and steady amongst the intense guitar riffs.
Better Things, Massive Attack (16/44)
The bass is buzzing and flowing and never overshasows the rest of the music. A test track to check on bass delivery and see how the DAC handles wide signals and micro-details.
Conclusion
The Graham Slee USB DAC is an absolute gem for such a price (it really is!), with a delightful sound. Its capacity to handle every type of music is extremely impressive. Do not focus on its looks: what matters is inside. Use this DAC without moderation! Just be sure to use a good quality USB cable, better yet, the excellent Audioquest USB Carbon.
