Slim Devices Transporter network music player

Is a high-end music server the audio equivalent of polishing a turd?

I've been hearing this put-down since I first became an advocate for digitally stored audio almost five years ago. At first, the argument was that computers had no place in a listening room. Wireless music servers took care of that argument. Then the big—and valid—concern was lossy-compressed formats, but ever-cheaper digital storage made uncompressed and losslessly compressed storage a slam dunk.

Well, said the still-unconverted, you can't argue that high-end DACs don't perform better than the cents-per-thousand mass-market chips included in players and server stations. A good point, but one quickly overcome by companies like Sonos and Slim Devices, who added digital outputs to their offerings.

But when I'd mention how good my combo of Slim Devices Squeezebox and Musical Fidelity X-DACV3 sounded playing my Apple Lossless Compression (ALC) files, several of my audiopals would still demure. "Surely you're not suggesting that a $300 front-end can sound as good as your Ayre C-5xe universal player?" Well, perhaps not—but near enough to clearly be high-end, and more than enough to offer hours of listening pleasure.

I must not have been the only one hearing such comments, because Slim Devices has now conjured up the Transporter, which it bills as "streaming digital music with sound quality that surpasses even the most exotic compact disc players." Everything about the Transporter has been designed to pacify audiophiles, from a hard-anodized chassis of "aircraft-grade aluminum" (per Slim Devices) to its backlit remote control to its component parts and, yes, DAC.

I guess some folks will still argue that a digital file, no matter how pristinely transferred and handled, is still a turd, but I guess it's all in the ear of the beholder. After all, I have a pair of cufflinks made from coprolite: dinosaur droppings that have, through the ages, become fossilized and quite beautiful, especially when treated as semiprecious stones.

In short, you can polish a turd. Properly processed, even the most unpromising material can become a thing of beauty.

The tourist transports his own values
The Transporter uses AKM AK4396 multibit/Sigma-Delta DACs and can accept digital inputs on coaxial, optical, and BNC S/PDIF, as well as AES/EBU balanced connectors. Internally, the Transporter, like the SB3 before it, carefully manages clock signals and employs special crystal oscillators and multiple stages of "super" power regulation, based on Walt Jung's designs. A word-clock input allows the user to sync to an external clock source, and the Transporter decodes WAV, AIF, MP3, WMA, and FLAC files with 24-bit resolution at a sampling rate of 44.1kHz, 48kHz, or 96kHz.

The Transporter's CPU is a 325MIPS, eight-way, multi-threaded device with an 8MB audio buffer and SlimDSP, a software-based digital signal processor (DSP) that resides in flash memory and is loaded into fast static memory "dynamically"; ie, as needed. This isn't conventional DSP of the sort you'd find in an A/V receiver; rather, it's designed to decode compressed files on the fly so it can transmit uncompressed 24-bit PCM over the network's WiFi link.

The Transporter has single-ended (RCA) and balanced (XLR) analog outputs, as well as coaxial, TosLink, BNC S/PDIF, and AES/EBU digital outputs. Ethernet and RS-232 inputs are also included. Analog and digital signal paths are kept separate. The balanced output remains consistent, but volume can be controlled through the single-ended outputs using a combination of digital attenuation and a set of resistor jumpers mounted on the circuit board: You set the approximate maximum volume with the jumpers and fine-tune with the digital attenuation. If you don't need to tweak it much with the digital control, you should be able to vary the volume without significant data loss. (Because I was using the Transporter with several high-end preamps, I kept the digital attenuation off during my audition, but it's there if you need it.)

One of the slickest features of the Transporter is its huge, two-part display, which is nigh on infinitely configurable. I generally used the left side to monitor whatever data were playing, and dedicated the right side to the nifty faux-analog VU meters to monitor the output. It was cool, if perhaps a little pointless. On the other hand, I had no need to scroll RSS feeds, weather data, sports scores, or other information across the display, so some harmless retro-visuals certainly didn't hurt.

Smack dab in the middle of the front panel is a large control knob, the TransNav, which employs dynamic tactile feedback to rapidly scroll through and choose from tons of information, including even the longest playlist. If you don't want to operate the TransNav up close and personal, the remote control offers an equal level of domination, though it lacks the same wow factor.

What hours of transport we shall spend
The Transporter, like the SB3, is far more versatile than a survey review can cover, primarily because Slim Devices is dedicated to open source development. Company head Sean Adams is obviously an immensely talented designer, but Slim also has a fanatical community dedicated to developing plug-ins and macros for the SB3 and the Transporter. If you desire a certain function, chances are someone else has too—and may even have created it. As Adams commented, "In a sense, with open source, we have more software developers working for us than Microsoft has thrown at Vista." Visit the Slim Devices Forums for a look at the possibilities.

Also working for Slim Devices is an unusually attentive and thorough customer-service staff. Although I had already downloaded and was running the SlimServer program on my Mac for my SB3, I had a small problem getting the Transporter to shake hands with my WiFi network. Dan of customer service talked me through it with good humor and patience. Late in the review, my Transporter refused to power on when I moved it downstairs for a final once-over. I called the help line again without identifying myself. Dan and I quickly tried a hard-power-on and a software-enabled power-up, and when both proved unsuccessful, he immediately said, "Let's get that bad boy back in here, so you can have it back before next weekend."

I was impressed and a little sheepish—I'd suddenly recalled an epic cat battle that had sent the Transporter crashing to the floor a few weeks earlier. It worked after that, but I'm betting that something was loosened enough to finally lose contact when I moved the unit downstairs. My bad. Well, Huckleberry's probably, but I'm a bad cat owner for not better securing the Transporter.

Three dollars and it only transports matter?
I integrated the Transporter primarily into my main listening room's he-man rig, which included my Ayre C-5xe universal player, K-1xe preamplifier, and MX-R monoblocks, Krell Evolution 202 and Evolution 600 preamp and power amps, and Dynaudio C-4 and Vandersteen Quatro Wood loudspeakers. All of these components are capable of highlighting minor differences, let alone compromised file formats, so I didn't bother auditioning lossy MP3s or, for that matter, Internet radio, which seldom gets above 128kbps.

It's not a matter of audio snobbery, it's merely facing reality: If your digital library isn't hi-rez, you don't need a Transporter. For this reason, I wasn't particularly disturbed that the Transporter couldn't play the few files I've downloaded from Apple's iTunes Music Store. It's true that I couldn't play them because of Apple's use of Digital Rights Management, but their 128kbps quality would have eliminated them even if the crippleware "protection" of DRM hadn't already done so. The same is also true of just about any other DRM'd download I can think of—the Transporter won't play 'em and I wouldn't have wanted to.

Dreams transport us through the underside of our days
I've already explained that I had to call Slim Devices' customer support to get the Transporter up and running, but after that relatively painless introduction, my experience was pretty much set it and forget it.

Forgotten, too, were such problems as searching a multiroom, multifloor warren of music rooms for the recording I wanted to play (or refile—as if I ever worried too much about that one). If I had the recording on my music library's hard drive, it was only a quick twist of the TransNav (or a few remote button presses away. And because I could search by artist name, album or song title, or genre, I could even find things I only vaguely remembered having, which made for a constant voyage of discovery through my own music collection. I thrilled to the mutual pleasure that the Grateful Dead got out of their 12-zillionth for-the-first-time-ever exploration of "Dark Star," on Hundred Year Hall (CD, Grateful Dead GDCD 40202). I marveled at the fluidity of Glenn Gould's traversals of J.S. Bach's Goldberg Variations (CD, Sony Classical/Legacy S3K 87703) late in the evening. The first thing in the morning, I had my eyes opened by Robert Silverman's incisive account of Beethoven's Diabelli Variations (CD, Stereophile STPH017-2).

And yes, beyond the effortless musicality, I was completely satisfied with the Transporter's sound. The bass was taut, the midrange unforced, the top end smooth and extended. The Transporter wasn't simply "good for what it was"; it was good.

Slim Devices
455 National Avenue
Mountain View, CA 94043
(650) 210-9400

Archimago's picture

Nice review for one of my favorite pieces of gear!

Truly "state of the art" measurements even compared to units many times the MSRP.

Over the years, I've often wondered what the jitter measurements would be like through the ethernet since in reality, I think most audiophiles would be running this unit wired rather than via WiFi to minimize buffer issues especially for 24/96 audio.

earwaxxer's picture

I have had this puppy since the 'nob' days. Just reread the review from 2007, one of the reviews I used to base my purchase of the Transporter on,  and reconfirmed what I think about this box. Part of me has lately had the yen to 'upgrade', since I have had it for 4 or 5 years now. I am coming to the realization now that I would STILL have to pay some big bucks, along the lines of a Berkeley Alpha DAC ll with USB converter to be sure it was really a step up. Now this observation requires some qualifications. First of all the Transporter HAS to be used via Ethernet to get the best sound quality. Second, redbook needs to be upsampled with min phase and dither applied with a good SRC (Sox) before it is sent to the Transporter. With those two things done I would love to read some reviews compared to ultra bux DAC's. -- Thats all for now! Probably write other comments in another 5 yrs or so...

earwaxxer's picture

Look, this hobby changes on a dime. I'm not saying I got rid of my Transporter. Actually the opposite. I recently went with JPS labs cables throughout. I know thats another topic, but to put it succinctly, it forced a reevaluation of all such connected equipment. Out was the tube preamp. The JPS cables reveled 'all' of it. Not a good picture. One the positive side I have gone to using my Transporter as a preamp. The sound is very good. I had put some considerable effort time and money into my DIY tube pre. A bit disappointed and excited at the same time. Plus one for the Transporter.

ednazarko's picture

One of the two Transporters I bought way back whenever just refused to turn on. (I am also using a modified Touch as the streamer to a DAC in another system... and another Transporter in an art studio system used mostly for streaming digital stations.) I've been spending some time trying to decide if I should spend the money on a repair attempt, or just spend money on a low end 2018 streaming DAC. This review popped up in my search... but more of my time this afternoon was spent listening to music streamed from Roon to my remaining Transporter, and to my other streamer/DAC combinations.

Beyond any doubt, for really high res files, my contemporary DACs win hands down. Which cost me about 3x the list price of the Transporter back in the day. (I bought one as a refurb for half retail, the other when Logitech was closing out, for about a third...) But when I listened to red book, even 24/96 files of rock and alternative, it was much harder to declare a winner. More interestingly, I have a number of compressed AAC and MP3 music files, from artists in poor countries, or from my early digital days. Odd, but the Transporter really sounds much better than contemporary high end DACs with those compressed files. Almost like the designers had thought through how to compensate for the failings of compressed files.

Logitech did an amazing job for the era. Roon's implementation makes it an easy integration today. Hope I can find someone who can fix the problem...

markreif's picture

Lost my Slimdevices Transporter Unit to old age this week. I have a Touch device I use in my basement system but my analog system in my family room demands higher quality. Found and ordered this ( as a replacement....