Slim Devices Transporter Digital Music Player 
Home Theater Media Servers Music Servers
Written by Brian Kahn   
Thursday, 01 November 2007

Whether we are in the car driving to the grocery store or on a plane suffering through yet another painful flight to somewhere, music lovers are able to access what used to be an impossibly large music collection right in the palms of our hands. Why shouldn’t we be able to do the same when we are at home? Over the past few years, has reviewed several top-notch music servers from the likes of ReQuest, Escient QSonix and others that give music lovers better than iPod audio quality, along with larger than iPod storage. In 2006, we reviewed the very affordable ($299) Squeezebox from Slim Devices (since purchased by Logitech) which differs significantly from the aforementioned competition in that Squeezebox does not have a hard drive to store music, but rather interfaces with your computer system to access the music files stored therein, as well as Internet radio.

The Slim Devices Transporter, which retails for $1999, is the big brother to Slim Devices’ Squeezebox music server. Like the Squeezebox, it can play both files you have stored on your computer network (PCs, TiVos, hard drives, etc.) through its SlimServer software, as well as being able to access Internet radio stations and dig into pay music services, such as Rhapsody and Pandora. While the Squeezebox is a small format box, the Transporter is built much more like a traditional audio component, a full 17 inches wide, three inches high and 12-and-one-quarter inches deep. Rack-mounting is an option. The aluminum-encased unit’s weight is not specified, but it definitely feels solid. The unit comes in either silver or black finish; my review sample is black and has a sleek, sexy appearance when paired with my reference audio system, which includes gear from MartinLogan and Krell.

The front panel is flanked by simple tubular silver metal handles, the bottom half of the front panel is aluminum with approximately 14 flush buttons in one row. The panel is dominated by a large TransNav knob in the center with a small Slim Devices logo above it. The knob controls several functions and provides tactile feedback. The top half of the panel consists of two vacuum fluorescent displays that can be configured to provide a variety of information and/or visuals. The most popular set-up appears to be text describing your listening selection on the left and retro VU meters on the right.

The back panel is fully populated and provides many options, with balanced and single-ended analog outputs, TOSLINK, coax S/PDIF, BNC S/PDIF and AES/EBU Balanced digital inputs and outputs; word clock input, IR input and output, Ethernet port, RS-232 jack, Wi-Fi antenna jacks and, lastly, an IEC power cord connector. The remote is a slim black unit that is very similar to the remote supplied with the Squeezebox, but it is backlit, which is a much appreciated detail.

The feature set described above is nice, but in itself does not set the Transporter apart from the pack. What the Transporter does is join the convenience of a music server with true high-end audio performance. Don’t expect to get audiophile performance from low-resolution MP3s downloaded from iTunes (not that the Transporter is capable of playing the iTunes songs encoded with digital rights management protection), but more excitingly, you can get a very high level of performance from high-resolution lossless and uncompressed audio files from your CDs or from new services selling higher-resolution downloads. iTunes users are not ignored by any stretch of the imagination, as iTunes playlists and catalogues are neatly recognized and playable by SlimServer, so long as the songs are not restricted by digital rights management.

The Transporter’s technical details are what sets its performance apart from the Squeezebox and other music servers, as it uses AKM AK4396 multi-bit delta-sigma DACs, with a signal to noise ratio of 1290 dB, THD of .00005 percent, linear super-regulated supplies for the DAC and line-out stages, word clock input for synchronization with an external clock and dedicated high-precision crystal oscillators. The Transporter is configured to support 44.1, 48 and 96 kHz sample rates with 16 or 24-bit depth. The supported audio formats include Apple Lossless, FLAC, WMA, AIFF, WAV, PCM, MP3, AAC, Ogg Vorbis, MP2 and MusePack. The architecture includes flash upgradeable firmware and a 325 MHz eight-way multithreaded RISC processor that allows for easy updates via download to make sure that your system can play the newest formats. There is much more to say about the technical aspects of the Transporter and its software and, for those of you who are interested, I highly recommend spending some time viewing the dedicated Wiki pages and forums, which are accessible through the Slim Devices web page. Last but not least, the Transporter has the audiophile attribute of not having a fan that interferes with listening.

As is the case with many products today, the Transporter does not come with the required software in the package. A quick visit to the Slim Devices website, and I was able to select and download the newest version of the Slim Server software, as well as browse the available plug-ins for future experimentation. System requirements include a computer system with Ethernet or Wi-Fi, and a computer system running Windows 2000, XP or Vista, Mac OS (10.3.5 or later), Linux/BSD/Solaris or Perl (5.8.3 or later). I personally use, and highly recommend, Infrant’s (recently acquired by Netgear) ReadyNas NV+ network attached storage device. I have the 1TB version configured in a RAID 5 array to give me about 670 GB of storage. I have the Slim Server software, as well as all of my music files on the ReadyNas NV+, so that I do not need to have my computer on to access my music collection. Furthermore, it is extremely reliable, never having gone down in the several months I have been using it and ensures that my music will be safe even if I lose a drive. Before purchasing a NAS device to do this with, be sure to check the Slim Devices support page to see which ones will work. You will want a device that can access the server software without the assistance of a computer.

Setting up the Slim Sever software is relatively simple. The set-up wizard asks basic questions and allows you to choose many options to personalize the organization of music and the behavior of the player. Ken Taraszka goes into some detail about the set-up in his article on the Squeezebox, which may be of interest to you in our archives. Once the software is set-up, you will need to populate your library. I already had iTunes and another music server on my system, both of which were recognized by Slim Server and their music catalogue.

There are many programs that allow you to rip music off of your CDs and onto your computer. When you add more music to be played back over the Transporter, you want to be sure that you are getting the best music quality possible. To do this, you need accurate rips and compression. I found Exact Audio Copy to be fairly simple and easy to use. The program is free to download and often comes bundled with format converters, such as one for FLAC. I downloaded this bundle and was accurately ripping CDs in just a few minutes. I note that it took me on average 20 minutes per CD to make the copy, which is much longer than most programs, but I have had no problems with dropouts with any of my Exact Audio Copy rips. Another easy way to get high-quality digital music files is to download them from high-resolution music download company Music Giants. The Transporter will play any of their non-DRM files. Unfortunately, you cannot yet use DRM status to search the fairly large database.

I began my listening sessions using my favorite integrated amplifier, Krell’s FBI. The FBI was connected to the Transporter via Transparent Cables’ MusicLink Ultra series cables, the Transporter was connected to my Theta Digital Data Basic CD transport via one of Transparent Cables’ older and, I believe, now discontinued basic digital cables. For speakers, I used my MartinLogan Summits, which were connected to the Krell via Transparent Cables’ MusicWave Ultra speaker cables. All of the above components were plugged into an EquiTech power conditioner with Richard Gray Power Company’s High Tension wires.

Towards the end of my listening sessions, I received a Conrad Johnson CT6 preamplifier and Nuforce monoblocks. With these components, I haven’t had enough time to decide if I prefer the Transparent or Cardas Golden Presence cables. While the Transporter had no weird compatibility issues with these newer components, all of my critical listening was done with the Krell-based system.

Lastly, I note that the output volume of the single-ended analog outputs can be adjusted two ways: first, through a series of resistor jumpers inside the unit, which let you adjust in 10dB increments, and second, through the use of the digital volume control. I left the analog attenuation at its default position of -0dB and left the digital volume control open all the way so as not to lose any resolution. If you must use the volume control in the Transporter, use the analog attenuation to get as close as possible in order to minimize any resolution loss through the digital volume control.

The Transporter can connect via the Internet to the Squeeze Network, which then connects to various third-party music providers, or it can connect to the Slim Server software on your local computer (or NAS), allowing access to your local music collection. Before listening to my same old music, I connected to the Squeeze Network and set up free trial accounts with Internet music providers Rhapsody and Pandora. Rhapsody has a large selection of current and vintage music to choose from, with many channels and direct access to a large number of artists. Pandora is part of the Music Genome Project and lets you create your own music stations based upon the music you like. To set up a station, you enter in songs and/or artists you like. Pandora uses the data from the Music Genome Project to find other songs that have similar identifiers and plays them on that channel. Other available providers include Radio IO and Live 365.

Given my past experiences with Internet radio, I had already decided not to make any sound quality judgments of the Transporter based on Internet radio sources. This said, the majority of the music I listened to sounded much better than expected. I purposefully sought out some tunes that I had in my collection in order to compare the Internet radio version to those already on my NAS. The lower resolution of the Internet radio music was readily apparent in several ways. The sense of space was extremely diminished, as was some of the texture in the vocals. On some albums, such as Amy Winehouse’s Back to Black (Republic), there was little difference between listening to the Internet radio or the locally stored version. For example, Winehouse’s hit “Rehab” sounded flat and one-dimensional, no matter what source I tried. I think that this was due more to the producer and engineers’ efforts to recreate a retro sound than to the playback system. On other albums, such as Norah Jones’ latest, Not Too Late (Blue Note), there is a jaw-dropping difference between the Internet radio and locally stored versions. Listening to the title track of Not Too Late, the local version seemed to have much more information in the upper registers and a better sense of the overall size of the soundstage, as well as much stronger positioning of the individual images.

I then moved on to listening to Shawn Mullins’ Soul’s Core (Sony), which I had both stored as a FLAC file and on CD. The song “Anchored in You” primarily features vocals and guitar. The FLAC and CD versions were nearly identical. Every once in a while, I thought I might have heard a slight difference, but without doing a double-blind listening test, I was unable to confirm this. Suffice to say that whether you use the Transporter as a music server getting a digital music file off of a hard drive or as a DAC with the music coming straight off a disc, you will be hard-pressed to tell the difference between the two. What does this mean? Not much, if the Transporter’s DACs aren’t very good. Thankfully, there is no need to worry, as the DACs in the Transporter proved to be extremely good. The unique characteristics of Mullins’ voice were readily identifiable and the weight of the lower guitar notes were just slightly light of neutral, but the detail and tonal accuracy were spot on.

Blues Traveler’s self-titled album (A&M Records) is a good test disc for me, as I have heard the band play most of these songs on several occasions. Listening to the opening track, “But Anyway,” I noticed that the Transporter struck a cohesive soundstage, despite a variety of instruments ranging from harmonica to drums. All of the instruments and vocals were well placed on an appropriately-sized soundstage, each of them easily followed, yet none of them overpowering the others. The tonal qualities of the harmonica were clearly reproduced, with none of the details getting lost among the instruments. The drums and bass guitar seemed just slightly lighter than normal, but with a great deal of clarity and presence. Those with good subwoofer set-ups will not be suffering from one-note bass syndrome. I found myself listening to the entire album; track after track, the transporter did a wonderful job of capturing the essence of the music.

While the bass notes seemed slightly lighter on the Transporter DAC than through my old Theta DAC, it was almost as though a veil was lifted when listening to bass notes through the Transporter as they sped up and were detailed without becoming overly analytical. This did not prevent the Transporter from delivering slam when needed. The synthesized bass notes in Crystal Method’s Vegas (Geffen) album and the bass line in Nine Inch Nail’s “Closer” off of their album The Downward Spiral (Nothing Records) both featured crisp, clean bass with solid but not overbearing weight.

Lastly, I went to audiophile-quality recordings, as the Transporter is designed to be an audiophile piece. Jennifer Warnes’ Famous Blue Raincoat (BMG / Classic) remains a favorite. The track “Bird on a Wire” has long been used as an imaging test. It did a good job in that capacity and also proved an excellent rendition of female vocals when I played it through the Transporter. Warnes’ husky vocals were solidly positioned in the center, the triangle was to the left where it belonged and the drums were a good distance back.

Before wrapping up the review, I compared the Transporter to my favorite CD player to date, the Classe CDP-202. Not surprisingly, I preferred the three-times-as-expensive Classe to the Transporter. For example, I listened to Elvis Presley’s rendition of “Fever” from Elvis is Back (DCC Gold) both through the Classe and the digital file off of the disc played through the Transporter. Both did an excellent job of capturing small details, such as the clinking of Elvis’ cufflinks and the sense of space of the soundstage. The differences were extremely slight. Through the Classe, I could more easily feel myself in the recording studio, the images were placed with a bit more precision and Elvis’ voice had a bit more body. Both the Transporter and the Classe did an excellent job of reproducing music with detail and accuracy, but the Classe had a sense of fullness and ease that the Transporter couldn’t match.

The Downside
The Transporter requires some computer set-up and knowledge to fully utilize. It requires some advance planning. You can’t just play a disc: the music has to be loaded onto the designated drive first, whereas the Escient has a built-in drive for spontaneous playback of a CD in hand, as well as being able to access music files off of a server. I would like to see better integration between Slim Server and Squeeze Network. For example, if I am listening to a song from my own hard drive via Slim Server, I could at the same time browse through other selections on Slim Server. However, if I want to see what is playing online through the Squeeze Network, the music playback stops, and vice-versa.
Sonically, I had no complaints. The Transporter performs as advertised. While it could not match the sonic excellence of the Classe CDP-202, I found it more than capable of holding its ground with other units within its price range.

Media servers are becoming more prevalent in today’s society. Music servers tend to come in two general flavors: those with built-in storage, such as iPods, Request and Escient, and those without, such as the Slim Devices units. The Slim Devices music players provide a whole-house audio system by allowing you to store all of your music in a central location and access it wherever you install a player unit, with each unit being able to either play its own selection or synchronize with each other for parties. The Slim Server music server software allows easy and quick access to your music or Internet radio.

Until now most similar systems were more difficult to operate and did not provide sound quality comparable to that of a high-end audio system. The Slim Devices Transporter delivers easy and immediate access to your music collection without compromising sound quality. If your system could benefit from a high-quality DAC as well as a music server system, I recommend the Transporter. If you already have a high-quality DAC with an extra input, check out the Squeeze Box and use its digital output to get the best audio quality. Either way, I would recommend that you set up the Slim Server software and your music collection on a NAS. This will isolate your music listening from computer crashes, as well as protect your music collection from hard drive problems.

In short, the Transporter provides an excellent way to keep your music collection at your fingertips without sacrificing sound quality.
Manufacturer Slim Devices
Model Transporter Digital Music Player
Reviewer Brian Kahn

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