Slim Devices Squeezebox

Slim Devices Squeezebox & Bolder Power Supply

On the right hand corner of my computer desk rests a 250-gigabyte external hard drive. Every once in awhile the face of the hard drive lights up, and the unit makes a soft whirring noise. At the same time, Allison Krause’s delicate voice fills the front room of my house. Sitting astride an Audio Magic Kukama digital to analog converter is a diminutive black box, with a large LED readout on the faceplate. To a casual observer this device could easily be mistaken for an everyday household item, such as an alarm clock. Upon closer inspection, this person would notice that the little black box displays the artist and song title of the music being played upon the stereo. This unobtrusive piece of electronics is called the Squeezebox, which is one the easiest ways to enter the world of computer based music storage.


Audio outputs (general)

  • Digital and analog outputs
  • All RCA connectors are gold-plated
  • Volume control is provided for all outputs
  • Multiple outputs may be used at the same time

Analog RCA outputs

  • High fidelity Burr-Brown™ 24-bit DAC
  • Two dedicated linear power regulators for DAC and line-out stages
  • Full 6.0Vpp line-level signals
  • Signal-to-noise ratio: over 100dB
  • Total harmonic distortion: less than -93.5dB (0.002%)

Digital S/PDIF outputs

  • Optical and coax digital connections
  • Dedicated high-precision crystal oscillators (no PLL, no resampling)
  • Standard IEC-958 (S/PDIF) encoding
  • Optical connector: TOSLINK 660nm
  • Coax connector: RCA, 500mVpp into 75 ohms
  • Sample rates: 44.1Khz, 48Khz
  • Audio format: linear PCM, 16 or 24 bits per sample
  • Intrinsic jitter: less than 50ps (standard deviation)

Headphone output

  • Standard 1/8″ jack also functions as an IR blaster
  • Minimum headphone impedance: 16 ohms
  • Total harmonic distortion: less than 0.03%
  • Left/right crosstalk attenuation: 92dB
  • Price: $299

In a system that utilizes a Squeezebox, a music library is stored on a computer system, which is typically located in a different room than the audio equipment. In order to use this device, the Slimserver program must be installed on the computer. This program is required to complete the interface between the Squeezebox and the software used to catalog the music. In a typical installation, the data is passed from the computer to a wireless router, which then broadcasts the information to the Squeezebox. From there, the Squeezebox can be used as a stand-alone digital player, or it can be used in conjunction with a digital to analog converter. A remote control allows the user to browse and select any songs contained in the music library that are stored on the hard drive. Actually, the Slimserver program allows the user to browse by artist, genre, album, or established play-lists. In most respects, the Squeezebox operates just like a conventional CD player.

Slim Devices Squeezebox review

The Squeezebox comes packed with a truckload of interesting features. I cannot describe every single one of them, but I will mention a couple that I found interesting. First of all, this unit is capable of accessing streamed music broadcasts. If you want to access radio stations that are on the web, the Squeezebox will allow you to do so. This makes it a viable alternative to a conventional AM/ FM tuner. The Squeezebox also has a news ticker feature, which allows the user to read up to the minute stories from a wide variety of sites, such as BBC World News or I can appreciate the Squeezebox ability to access a music service named Rhapsody. It is a fee-based service, but this allows the user to have a massive catalog of music to listen to. I have only scratched the surface of what functions are built into the Squeezebox, there are several others that may appeal to others besides me. The convenience and flexibility of this unit is mind boggling, and anyone owing one will be sure to find a way to utilize its other features.

The music server that I use is contained on a Western Digital external hard drive. This drive is slaved to a Dell Inspiron 1100 computer system. The data is relayed to the Squeezebox by an Actiontec wireless router. I use Apple’s i-tunes program to organize the music burned to my hard drive. The Apple software has a simple layout, and is easy to navigate. There are a few adjustments to the default configuration that needs to be made in order to obtain the highest sound quality. The word length for i-tunes needs to be switched to the 24-bit setting. The volume control also needs to be placed at 100% output. It is also important to turn off any sound shaping features, such as the internal equalizer program. All of these features operate in the digital realm, and therefore change the data stream. My goal is to have the data passed through the computer system in its original form, so that I could make a fair comparison of the Squeezebox to a conventional CD player.

Making a few adjustments within the Slimserver program can optimize the sound quality of the Squeezebox. The data stored on the hard drive is in WAV file format, which is an uncompressed configuration. I chose to have the Slimserver program send the data as WAV files, instead of converting it to the FLAC format. I know there is spirited discussion on the sound quality of FLAC encoded music, but I fall into the camp that feels it compromises the music. There is a volume compensation feature within the Slimserver program that needs to be defeated. This option allows the Squeezebox to make automatic adjustments to the output levels of different discs in order to keep all music at the same overall volume. Once again, this is accomplished by altering the data stream, and other Squeezebox users have noticed degradation in overall sound quality with this option engaged. It took some time and effort to learn the ins and outs of fine-tuning the Squeezebox. With timely support from both the Slimdevices technical support staff, and the Slimserver on-line forum, I did not come across any issues that couldn’t be easily resolved.

I have a weakness for low powered tube amps and high efficiency speakers. Out went a fine pair of Monarchy amps that were used in last review, and I returned my system to my favorite configuration. A pair of Electra-Print 300 DRD mono-blocks took care of amplification duties. An Electra-Print PVA preamplifier controls the amps, which is a transformer-based design. The speakers used for this review are a set of Audio Nirvana Super 12 drivers, which are housed in Lovecraft Design cabinets. The Squeezebox was often paired up with the Audio Magic Kukama digital to analog converter. A JVC XL-Z1050TN CD player provided my reference point for comparing the performance of the Squeezebox as a source for the DAC. Speaker wires, interconnects, and digital cable are from the Audio Magic Illusions 4D line. Audio magic Extreme power cords were used on all components with a detachable IEC cord. A Monarchy AC Regenerator handles power conditioning for source units. Part way through my listening sessions, two aftermarket power supplies became available for the Squeezebox. These latecomers changed my opinion of this unit, and radically altered the final outcome of this review.

Slim Devices Squeezebox back

Having your entire music library at your immediate disposal is a fantastic experience. The Squeezebox brings a level of flexibility and convenience that can only be approached by the big CD jukeboxes that are offered by Pioneer or Sony. Without a doubt, this unit has all the features necessary to make it a viable music controller. With a modest price tag of 300 dollars, I was curious about what level of sound quality could be achieved.

The Squeezebox broke in for several weeks, and during this time I educated myself about the finer points of setting up the Slimserver software. In the first listening session, the Squeezebox was used as a standalone digital source component. While the unit performed quite competently, its sonic abilities were only on par with a modestly priced CD player. “Only A Dream” by Mary Chapin Carpenter [Come On Come On; Columbia CK 48881] has a haunting piano melody that never fails to draw my attention. The Squeezebox loses the ambient information in this piece, and the piano takes on a metallic haze. Carpenters vocals also sound slightly constrained and glossed over. Finally, the size of the soundstage was restricted to the plane in between the speakers. The music did not project itself into the room, and create a believable soundstage. Overall, I was disappointed in the performance of the stock Squeezebox as a stand-alone digital source.


Clearly the internal D to A converter in this unit was not up to the task of creating high quality music. Given its modest price tag, I was not expecting great sound the player. The next logical step was to partner the Squeezebox with an Audio Magic Kukama DAC. The connections were made with an Audio Magic Illusions 4D digital cable from the digital out jack on the Squeezebox. The Mary Chapin Carpenter song was pressed into service once again. This combination resulted in a significant improvement in sound quality. Carpenters voice filled out, and took on a darker hue. The piano lost the metallic edge to its tonal balance, which was clearly evident in the previous configuration. The size of the soundstage grew in terms of width and depth. As a whole, I would have to say that the Squeezebox began to approach the performance level set by my conventional transport. There was still one critical area that the Squeezebox lagged behind the CD player. The JVC did a better job at presenting the ambient cues found in the recording. Piano notes hung in the air a little longer, and the hall reflections were brought to the forefront with the CD player. Still, I found the Squeezebox/Audio Magic combination pleasant to listen to. Given the convenient nature of the Squeezebox, I could envision it being used in a wide variety of systems, especially if it were partnered with a respectable DAC. In terms of sound quality, a stock Squeezebox and DAC combination will still fall short of the high end conventional digital front-end packages.

The wall-wart power supply that comes with the Squeezebox is the Achilles heel of this product. If you search the net, there are many discussion threads about how a different power supply will improve the sound quality of this unit. Halfway through the review, I was offered a pair of aftermarket power supplies from Wayne at The Bolder Cable Company. One unit is a stock ELPAC power supply, which can be found on EBAY for approximately 40 dollars. The second unit is also an ELPAC that has been extensively upgraded. Wayne removes all the passive parts from the circuit board, installs some HEXFRED diodes, and upgrades the reservoir capacitors. Naturally, I decided to take Wayne up on his offer. If the performance level of the Squeezebox could be taken to another level, I definitely wanted to hear it. Since the highest level of performance was achieved with the Audio Magic DAC in the system, I decided to leave it in place while I evaluated the power supplies.


The stock ELPAC power supply is a significant upgrade to the Squeezebox. The stock ELPCA went into the system first, in order to determine the level of improvement that can be had from an inexpensive upgrade. Just form a visual inspection; it is quite apparent that the ELPAC is a superior unit to the wall-wart. In order to keep the evaluation consistent, I once again cued up the Mary Chapin Carpenter disc. The changes to the sound were readily apparent. The ambient information that is lost in the previous listening session can now be easily heard. The piano notes have a longer decay, and transition smoothly into the next note.
The reverberation patterns that were lost by the stock Squeezebox can now be heard. It is once again easy to hear the distinct presentation of this venue. Lower register piano notes also gain weight and authority. Considering the modest price of an ELPAC power supply, I would have to say this upgrade is a definite “no-brainer”.

While the stock ELPAC results in a noticeable improvement in the performance of the Squeezebox, I was not completely satisfied with the end result. The Squeezebox/ELPAC combination can sound coarse and rough at times. The overall presentation of the Mary Chapin Carpenter disc is slightly harsh. This limitation makes itself apparent in the tonal balance of the piano. Basically, the piano just sounded somewhat unsettled. The JVC maintains its composure during this song, and the piano has a refined quality in this recording. While the stock ELPAC power supply is a great ”bang for the buck” upgrade, the Squeezebox sound quality can still be improved.

The Bolder Cable Company has spent significant amount of time developing upgrades for the Squeezebox. The modified ELPAC supply is essentially the first revision that can be had for the Squeezebox. This modification will set you back 120 dollars, plus the cost of the ELPAC. My ears tell me that this is money well spent. The Bolder modified power supply retains all the strengths of the stock ELPAC, but it effectively removes any residual harshness that is found in the unit. When I played “Only A Dream”, the piano now sounded smooth, yet there was no loss of detail. The soundstage expanded slightly, and the room reflections became quite distinct. Carpenters voice lost a small amount of grain that was difficult to discern in previous listening sessions. It is true that the stock ELPAC power supply resulted a significant improvement in sound to the Squeezebox. The Bolder modifications finish the job, and turn the Squeezebox into an authentic high-end source component. I decided to revisit the Squeezebox as a standalone player once more. With the Bolder modified power supply being introduced into the mix, I had high hopes for this listening session. This time, the Bolder modified power supply is being introduced into the mix. My previous listening session with the Squeezebox as digital source left me under whelmed, but I now had high hopes for this round. My expectations were not unfounded, and the Squeezebox/Bolder combination turned in an inspired performance. For this listening session I moved on to some different music, because I could not listen to Carpenter disc one more time. I scrolled through the artist menu on the Squeezebox, and selected “Which One” [Get Me Some; Forte 75181101] from the Jeff Healy Band. I had listened to this cut during an informal listening session with the stock Squeezebox, and at that time the song was barely tolerable. The music was harsh, while the soundstage was as flat as a pancake. The difference in sound quality in this listening session was quite striking. Now the Squeezebox goes through a metamorphosis, and turns into a high quality digital component. The music loses its harsh and metallic tone that characterized the stock unit. Soundstage width and depth expands dramatically. The Jeff Healy Band generates a lot of energy, which the Squeezebox portrays in a realistic manner.

While every facet of performance increases with the use of the modified power supply, there is still one major issue that I could detect with this configuration. Quite simply, the bass response of the Squeezebox is not on par with the Audio Magic DAC. The bass guitar and drum kit does not have the extension or impact that can be heard from a high quality digital to analog converter. Honestly, this is not a fair comparison since the Kukama retails for $2500, while a Squeezebox with Bolder power supply sells for just under $500. I would venture to say that the Squeezebox is capable of reproducing at least 85% of the sound quality of the Kukama. I understand that Wayne has a whole series of upgrades available for this unit, and there is still room for significant improvements to be realized.

When I was sitting back on my listening couch with the Squeezebox remote in hand, I find myself amazed at how convenient this product is to use. Having an entire CD collection at your immediate access is quite a luxury for any audio enthusiast. The Bolder Cable Company power supplies are a must have for anyone requiring high quality digital playback from their Squeezebox. The stock ELPAC power supplies are quite good, but the Bolder modifications unlock the true potential of the Squeezebox. It takes a little bit of work to optimize this unit, since there are several settings in the Slimserver program that can affect sound quality. With the support of the Slimserver online community, I found this process to be quite manageable. The Squeezebox is useful tool to anyone who needs to interface a computer based music server to an existing DAC. The combination of Squeezebox with the Kukama DAC is capable of high-end sound reproduction. The Squeezebox would be a welcome addition to my system, provided I used the Bolder modified power supply. There is a lot of potential to be squeezed out of this little black box; it just requires a bit of time to learn the nuances of the system. In my opinion, the results are well worth the effort.

from affordableaudio, By John Hoffman