My Foray into Digital PC-Audio (Part 2) By Alan Nastir In my last column, I summarized my experience (to date) setting up a streaming digital audio server using Exact Audio Copy to rip my CD's to FLAC files, and then storing them remotely on a Buffalo Linkstation. In this column, I'll finish describing my setup and present some opinions (mine and others) about whether such a system can truly deliver an audiophile experience. Once you've gotten your music files (FLAC, or equivalent lossless format) stored somewhere on a PC, or (in my case) networked attached storage, the final step is delivering them to your audio system. You basically have two choices here-- local playback, or network streaming. If you're able (or brave enough) to locate a computer adjacent to your audio setup, you can simply use the computers sound card to stream digital music out via S/PDIF or TOSlink to an outboard DAC (or Pre/Pro with a native DAC). PC-audio enthusiasts recommend upgrading to a high quality sound card that bypasses the evil Windows "Kmixer", which reportedly adds garbage to digital audio streams. Apple users are immune from such nonsense. Conversely, Xitel offers their Pro Hi-Fi Link (www.xitel.com/product_phfl.htm), which is an outboard USB connected Sound Card/DAC combo. One downside to local playback is the possible introduction of mechanical noise and/or EMI into your setup. Another is that local playback usually requires using the computer screen and keyboard in lieu of a remote control. Conversely, a TCP/IP networked device offers some compelling points, including remote location of the computer/server, and capability for simultaneous multi-room streaming. TCP/IP networks also have very robust error correction, which makes them ideally suited for streaming audio. Networked media servers are a rapidly growing niche. In fact, Sound & Vision (that highly regarded audiophile rag ) reviews three such devices in their current issue. Just my luck, as I had spent countless hours online researching such products… including those from Apple, Sonos, Roku (SoundBridge), and SlimDevices (Squeezebox2). Among the competition, Apple (of course) offers a very compelling product… the Airport Express (http://www.apple.com/airportexpress/), which actually runs on both Mac or PC. It streams iTunes managed music collections in any of Apples supported formats (including their proprietary ALAC lossless files, equivalent to FLAC in quality). However, it does not support FLAC files at all, and does not offer a remote control. The Roku SoundBridge (www.rokulabs.com) and Sonos products (www.sonos.com) have also garnered good reviews. The latter has a slick color LCD controller, which retails for $400 alone! Although both support streaming FLAC files, they seem more geared to mainstream (MP3 type) consumers. After all my research, I ultimately chose to go with the SlimDevices Squeezebox2 (hereafter referred to as SB2). It's a cute little box that sits adjacent to your audio setup, and connects via RCA analog out, or S/PDIF or Toslink digital out. It has no moving parts, and is totally silent. It grabs your music files from anywhere on your network, and passes them to your system. It requires the companion SlimServer software to be running somewhere on the network. Some of the reasons I chose the SB2… ¨ The company, SlimDevices (www.slimdevices.com), is solely focused on audio. Photo and video streaming are not part of their gameplan (at least for now ). ¨ Unlike it's competitors, the SlimServer/SB2 software/hardware combo was designed specifically for FLAC from the ground up. It actually converts other formats to compressed FLAC, before streaming, thus saving network bandwidth. This allows even a slower Wireless B network (max 11 Mbps), to still be more than sufficient for streaming audio. The SB2 hardware then decompresses the incoming FLAC files on the fly. (The SB2 box actually uses Wireless G, max 54 Mbps, which is backwards compatible with B). The SB2 also includes a Cat5 Ethernet connection, for those who already have wired network access near their audio system. ¨ The SB2 has a highly configurable high-res vacuum tube display, and a simple, yet robust alphanumeric keypad. Together, they provide a Tivo-like cascading menu that easily controls all functions. The SlimServer software can also remotely control the system. ¨ The SlimServer software is open-source (running on Mac, PC, or Linux), and there is a large developer community hell-bent on pushing the envelope with their software plug-ins. For instance, you can view musician Biography info on the display, based upon which CD artist is playing at the time! ¨ Slim has also just introduced the SlimNetwork, which provides streaming Internet Radio, and Live Recorded Concerts, with more features to come. ¨ Lastly, while also catering to the masses, the folks at SlimDevices seem genuinely committed to providing audiophile quality sound for users with high-end systems. Their CEO (and apparent Chief Technology Wizard) Sean Adams is active in the audiophile section of their support forum, even sharing detailed engineering specs with DIY audiophiles who are already experimenting with SB2 mods. For those afflicted with Audiophilia Extremis (a terminal condition), the SB2 was even engineered to minimize "jitter"… as detailed in their FAQ Audiophile Section… "The S/PDIF interface and DAC clocks are driven directly by two dedicated crystal oscillator circuits running at fixed frequencies. By contrast, other low-cost devices generally use a PLL circuit to generate multiple clock frequencies from a single crystal - this design is less expensive, but it is more susceptible to instability due to power supply noise and environmental factors. By using dedicated fixed oscillators, Squeezebox2 eliminates the predominant source of jitter and clock imprecision in S/PDIF sources." The entire Audiophile FAQ description (quite an interesting read) can be found here… http://www.slimdevices.com/pi_faq.html For you analog/tube mavens, check out this design proposal from one of the online SB2 aficionado's . Ulimately, specs and software features aside, the proof is in the listening. At the time I hosted last months TBLS meeting, I had just barely cobbled together my system, and was still tweaking the myriad options that SlimServer/Squeezebox2 offers. Even so, I rated my setup as approaching, perhaps, 90% CD-quality (given the acoustic limitations of my equipment, room, furniture, and WAF). Many agreed, others snickered! In the subsequent few weeks, I have relocated the SB2 from sitting directly on top of my center channel speaker, which (although "magnetically shielded"), was, I believe, degrading the sound. I have also switched from TOSlink to S/PDIF outputs. Those tweaks have significantly improved my soundstage depth and imaging. I eventually plan to test the SB2 with an outboard Benchmark DAC1 (thanks Mike!). Lest you think I'm biased in my religious fervor about the SB2, here are some comments from others, excerpted from the SlimDevices Audiophile Forum.. ”So far the digital out of the SB2 is proving to be at least as "good" (if not "better") than various serious CDP's (e.g Linn Ikemi, Unidisk 1.1, CD12, various Naim's, Levinsons and so on...your systems and experiences will vary!" "Just received my SB2. Like most everyone else, setting it up took less then a minute. I am a serious audiophile. My 2 channel setup as follow:Linn CD12 and Linn Unidisk 1.1 as sourcesPlacette Audio Custom made fully balanced Passive preampTacT RCS2.0SMark Levinson No.33HRevel Ultima SalonI have been ripping music into Lossless using EAC. With a lack of a better option, using the TacT DAC, the sound quality is already impress me enough to convince me that my 20k Unidisk should go on Audiogon soon! The SB2 is simple to operate. I wish it had an option for a TV out so I could use my plasma to choose music and create playlists, but as of now, it is one very functional unit." ”Yes, a dedicated, external DAC can be superior to the SB2's internal DAC. However, this isn't a given: I've already observed that the Scott Nixon Chibi Saru is inferior to the lone SB2, until you add a good power supply. Then it does surpass it by a bit, but not a lot. IMO, the SB2 is that good!" In summary, whether one embraces the subjectivist or objectivist point of view, the bottom line, ultimately, is whether a system puts the AHHH back into audio. For me, the SB2 does precisely that. I look forward to tweaking my setup further, and am anxious to hear what the SlimDevices developer community comes up with next. Bottom line… ¨ Time spent ripping my entire CD collection to FLAC… 100 hours. ¨ Cost of my entire streaming digital audio setup (Buffalo Linkstation and SB2)… $750 ¨ Value of being able to sit in my sweet spot with remote in hand and access my entire music collection at the touch of a button… PRICELESS!