Budget USB DAC Survey

Digital-to-analog converters
Blue Circle Audio USB Thingee,
High Resolution Technologies Music Streamer+
Budget USB DAC Survey

I love music and inexpensive high-performance audio products. While I love music more, occasionally I get a product I adore almost as much as the music itself. Consider that a hint as to my feelings about one of the three products I’m about to review. But all three offer an elegant path from a computer’s USB to analog music for less than $300.

Circular Logic

“Don’t Fight the Funk!” could be the corporate motto for Blue Circle Audio. Founded in 1988 by Gilbert Yeung, and based in Innerkip, Ontario, Canada, Blue Circle produces a complete line of products including preamps, power amplifiers, cables, and what must be among the strangest audio products ever devised, the Music Purse and Music Pump (available at classicpumps.com/mpumps.htm). These last products are a preamp in a purse and a pair of monoblock power amps encased in a pair of women’s high-heeled pumps. Fortunately for those of us who aren’t fashionistas, most Blue Circle products are housed in more conventional packages.

The USB Thingee’s aesthetics sit at a halfway point between your standard black audio box and the Music Purse. The entire Thingee resides inside a dark gray PVC tube 3½" by 2¼" in diameter. All its innards are potted in translucent silicone, which Blue Circle uses because “the silicone helps to avoid external vibration and, with the PVC pipe, makes the USB Thingee very strong.” It also gives the USB Thingee a decidedly homemade look.


A Thingee Is as a Thingee Does

The Thingee functions as both a digital-to-digital converter and a DAC. It is available in four versions. The basic $169 USB Thingee has a USB input and an S/PDIF RCA digital output as well as an analog 1/8" stereo output and a pair of RCA analog outputs. For $179 you can have an additional AES/EBU digital output or a TosLink digital output. For another $10 up-charge you can get a USB Thingee with both of the additional digital outputs. That’s the unit I was sent for review.           

The USB Thingee supports both 44.1/16 and 48/16 digital outputs from USB. It will not support higher bit rates. I used it successfully as a digital converter with a variety of stand-alone DACs including the Bel Canto DAC3, April Music Stello DA 100, and the Meridian 518/561 combination. In every case the Thingee successfully interfaced and transmitted a digital music stream with no compatibility issues whatsoever. If you have a high-end DAC that lacks a USB input, the Thingee serves as an excellent bridge device to bring computer-based music files into your DAC.

I compared the Thingee with the built-in digital TosLink outputs from my Mac Pro Dual-core Intel Xeon computer. In direct matched-level A/B comparisons I couldn’t hear any sonic differences. So with the Mac Pro the USB Thingee’s primary appeal won’t be sonic but ergonomic—it delivers the option to connect with DACs that don’t have TosLink inputs (which many high-end DACs have dumped). The only connection that did yield a subtle but noticeable sonic improvement was when I hooked up the USB Thingee’s AES/EBU output to the Meridian 518/561 combo. This connection had slightly better depth and image specificity. With other computers you may well hear more differences between their internal digital converters and the Thingee since some computers, especially portables, have converters inferior to those in the Mac Pro.

Although the USB Thingee worked nicely as a bridge device between my Mac and a wide array of standalone DACs, it was less sonically successful as a one-piece DAC. It puts out only 0.775V RMS, which may be insufficient for many passive preamp systems. Through the Reference Line Preeminence One preamp (which is a passive unit) it produced adequate volume but the sound was flat with a one-dimensional, mechanical character. Compared to other DACs the Thingee’s sound lacked midrange bloom and musicality. Every other DAC I had in house, including even the $89 High Resolution Technologies Music Streamer USB DAC, sounded far more natural and appealing through the Reference Line preamp. When I hooked up the USB Thingee via its analog output to the Meridian 561 (which uses the Meridian’s internal A/D to re-digitize the signal) the sound was less astringent but still less dimensional and less harmonically full-bodied than the direct digital feed from the USB Thingee’s digital outputs to the Meridian. Finally I hooked the USB Thingee up to a Dell D620 portable. The Thingee’s analog output sounded slightly better than the Dell’s own internal soundcard.

While I would unequivocally recommend the USB Thingee if you need to transform a digital musical stream from USB to coaxial S/PDIF, TosLink, or AES/EBU, if you want to use it as a D/A device for going from digital to analog you would be sonically better served by other options, including the High Definition Technologies Music Streamer.

Musical Notes from a Digital Stream

Michael Hobson of Classic Records and Kevin Halverson of Muse Electronics officially launched High Resolution Technologies at the 2009 CES. Their stated goal was to produce budget-priced high-performance specialty products for the digital music age. Their first offering, called the Music Streamer, is a USB DAC with a list price of $99. Can ten sawbucks actually get you a satisfying DAC? Oh yes, it can.

The Music Streamer doesn’t look like much. It’s a small, 4"-long, red, hexagonal box with a USB connection on one end and a pair of RCA analog outputs on the other. Inside you’ll find a small USB input board suspended on top of a larger circuit board with the surface-mounted RCA outputs. It is powered by the USB connection with no provisions for an outboard power supply.

I picked up a Music Streamer DAC at HRT’s official press conference at CES. It took me a couple of weeks to clear the decks of prior commitments before I could install it in my desktop-computer music system. At first I couldn’t believe I was listening to the $99 Music Streamer—I immediately dove under my desk to check all my cable connections and opened the sound settings in my Mac’s System set-up panel to ensure I was listening to the Music Streamer rather than the April Music Stello DA100 that was also in my system. But I was listening to the Music Streamer! Even cold and unbroken-in the Music Streamer sounded startlingly good.

Unlike many inexpensive DACs, which may sound clean but lack the “juice” that makes recorded music sound right, the Music Streamer retains music’s essential harmonic richness. Instead of a mechanical facsimile of music, the Music Streamer delivers that special spark that our brains immediately identify as the real thing. Even 320kbps MP3 music files played through the Music Streamer have a musical rightness that very few DACs, regardless of price, manage to convey.

Even the most hard-core detail freak will smile when he hears the low-level resolution the Music Streamer delivers. On the flute introduction of Muireann Nic Amhlaoibh’s tune “Humours Of Whisky” from Daybreak: Fainne anLae it was easy to separate out the flutist’s breath from the harmonics of the flute itself. This particular cut was a 320kbps MP3! On another MP3 file, Norah Jones’s “Don’t Know Why,” each back-up singer’s voice had its own unique spatial envelope. The electric and acoustic guitars also retained their individuality even when they played the same melody lines. A final example of the Music Streamer’s ability to retain and delineate musical subtleties, on my MP3 copy of Bryan Sutton’s album Ready To Go mandolinist Sam Bush’s right-hand attack comes through with his rhythmic pulse fully intact.

So what doesn’t the Music Streamer do well? When I compared it with the Stello DA100 D/A I noticed the Stello has slightly better back-to-front depth and three-dimensionality. On my own live concert recordings I was more conscious of the spatial separation between the individual players through the Stello than through the Music Streamer. Harmonically these two units were scarily similar, which means either they were both wrong or they were both right. I strongly suspect the latter.

For under $100 the Music Streamer qualifies as the biggest bargain I’ve heard in a long time. Try it and prepare to be amazed.


Plus Versus Minus

Any TV viewer who’s found himself or herself face to face with a late night infomercial has probably heard this phrase, “But wait, there’s more!” This bit of infomercial jargon rattled around in my brain when I first installed the Music Streamer+ in my system. But unlike overly hyped late-night trash hawked over the airwaves, the Music Streamer+ delivers as promised. It provides all the performance of the basic Music Streamer plus an additional dollop of depth, inner detail, and musical finesse.

Physically the Music Streamer+ closely resembles the basic Music Streamer. It’s a similarly shaped hexagonal box, but the box is a satin-finished gray and slightly bigger. Inside is the same circuit-board layout. The upper USB-interface board appears to be identical to that of the original unit. The front half of the lower board is also very similar to the standard Music Streamer, but the back half of the board, closer to the RCA analog outputs, is very different. The Music Streamer+ has a PCM 1794 D/A chip instead of the PCM 1744 on the standard Music Streamer. Also the Music Streamer+ has a far more sophisticated and robust analog-output topology with four individual op-amp ICs.

The Music Streamer+’s specifications boast 21dB better signal-to-noise, a 100uV RMS lower A-weighted noise floor, and 0.04% lower THD. Because the standard Music Streamer is so quiet, meaning I heard no noise whatsoever even at maximum listening levels, I wondered if these better specifications would translate into better sound. In level-matched comparisons (made easier because the two Music Streamers have the same output levels) I quickly noticed that the Music Streamer+ wasn’t noticeably quieter or higher in resolution or inner detail, but it did deliver greater three-dimensionality and more precise image specificity. While the basic unit hadn’t quite matched the imaging capabilities of the Stello DA100 D/A, the Music Streamer+ delivered every bit of the dimensionality of the Stello. In matched-level tests between the Stello and Music Streamer I could not reliably tell one from the other.

A Dyna Stereo 70 Epiphany

Near the end of the review period I replaced a pair of Bel Canto Ref 500 monoblock amplifiers in my desktop system with a “new old-stock” Dyna Stereo 70 I had purchased at the Denver Vintage Voltage Audio Show. This Dyna has a stock circuit, but new tubes, resistors, and capacitors. The system signal path was as simple and straightforward as possible—it went from the Music Streamer to a Reference Line Preeminence One passive pre to the Stereo 70 and finally to the speakers. The signal chain didn’t have a single transistor in the circuit except for the op-amps in the Music Streamer+ itself. I was floored by how good it sounded. No, not good, stunning.

I’ve been using various solid-state Class A, B, and D power amplifiers for the last five years or so. Perhaps that was a mistake. In the interim I had forgotten how electronically grainless a tube amplifier can sound. I’d also forgotten just how much depth a solid-state amplifier removes from the soundstage. Even the “lowly” Dyna Stereo 70 tethered to the Music Streamer+ delivered so much additional spatial information that the expression first used by Harry Pearson (with a bow to Coleridge) to express the depth characteristics of solid-state power amplifiers— “paper ships upon a paper ocean”—was still very appropriate. Even commercial pop recordings on MP3 files displayed spatial characteristics that I’d never heard before. Soundstaging details jumped out and virtually slapped me in the face, as if to say: “Stone, you ignorant ninny.”

After a couple of days I went back and compared the Stello DA100 D/A to the Music Streamer+. Again in matched-level tests I couldn’t discern any sonic differences between these two D/As. On Hal Ketchum’s latest CD, Father Time, which was recorded live in studio without overdubs, the soundstage width and depth through both units went well past the outer edges of my monitor speakers. On my own live concert recordings it was easy to separate out the directly radiated sounds from the reflected sound coming off the back of the stage.

Stream On, Stream On

The Music Streamer+ may be an even bigger value than its little brother, the Music Streamer. Couple it with transparent electronics and a pair of good speakers and be prepared to get closer to your music than you ever thought possible from a $299 USB DAC. It may not support 96/24 or other higher-resolution digital files, but what the Music Streamer+ does for 44.1 and 48kHz 16-bit music files must be heard to be believed.


Associated Equipment

MacPro Dual core computer with iTunes 8.1, Meridian 518, Meridian 561 pre/pro, Reference Line Preeminence One, April Music Stello DA100 D/A, Spender SA1 speakers, ATC SCM7 speakers, Paradigm S1 speakers, Earthquake Supernova Mk IV 10 subwoofer, Goertz M12 Veracity speaker cables, Goertz TQ2 alpha-core interconnects, MIT AVT1 interconnects.


Blue Circle Audio USB Thingee

DAC: Internal 16-bit/44kHz (can transfer up to 16/48)
Analog output: 0.775V RMS
Price: $169 and up (varies with output options chosen)

Innerkip, Ontario, Canada N0J1M0 
(519) 469-3215

High Resolution Technologies Music Streamer

Output: 2.25V RMS
Frequency response: 20Hz–20kHz +.3dB/-1.8dB
S/N ratio: 82dB
Input data: 44.1/48kHz, 16-bit
USB type: 1.1
Dimensions: 4.1" x 2.1" x 1.2"
Price $99

High Resolution Technologies Music Streamer+

Output: 2.25 Volts RMS
Frequency response: 20Hz–20 kHz +0 dB/-1.7dB
S/N ratio: 100dB

Input data: 44.1/48kHz, 16-bit
USB type 1.1
Dimensions: 5.1" x 2.1" x 1.2"
Price: $299

(323) 967-7447


Interview With High Resolution Technologies' Kevin Halverson

SS: Why and how did High Resolution Technologies come about?

KH: I think you already know that High Resolution Technologies is collaboration between Michael Hobson and myself. Michael and I have worked together on a number of projects over the years. We collaborated on things like the original Classic DAD release (PCM DVD discs) and specialized hardware and software solutions for the premastering and disc authoring industries. We also worked on the HDAD series of DVD-A/V discs. This latest collaboration is a continuation of the our past efforts to bring higher quality to the digital audio experience, now applied to computers which are quickly becoming mass-storage music jukeboxes.

The idea for High Resolution Technologies and the Music Streamer line came about when Michael came back from a trip to Europe last summer and mentioned to me a USB-connected DAC he saw in Switzerland. We spoke about it and I offered that there were things that could be done to improve upon what he had heard. Eight weeks later we introduced our first two products—The Music Streamer and The Music Streamer+ at the Consumer Electronics Show.

SS: What did you find when you examined USB DACs?

KH: Generally, they all missed several important factors (at least in my opinion) when considering any computer-sourced listening. Specifically, they did little, if anything to address the inevitable contamination that can result from the common connection between the computer and the audio system. Most designs that I looked at also improperly handled their power supplies and analog output stages for this type of application.

SS: What did you do differently in the Music Streamer?

KH: A few things really. Some of the differences include a topology that provides complete isolation between the computer side and the audio side, a unique HF power supply for the USB transceiver and audio sides, and unique jitter suppression.

SS: What differentiates the Music Streamer from the Music Streamer+?

KH: Besides the obvious price difference, the important difference is their performance. There is a considerable difference in the converter topology, reconstruction filters, and output buffer of these two products.

SS: Do you see them for different markets or users?

KH: The price differentials and our expectations of sales volume are vastly different for these two models. The Music Streamer should be considered a moderate-priced product for the average consumer; in the hi-fi world it might be considered absurdly inexpensive. One of the goals was to develop a product that could sell to a wider portion of the population; the Music Streamer directly targets these individuals. The Music Streamer+ is intended for more seasoned audiophiles and for those that have systems that justify and allow for the appreciation of the performance differences.

SS: Why did you choose 2.25V output for both?

KH: Nearly all USB-powered devices suffer from inadequate output magnitude, which typically results from the limitations of the USB-bus power-supply level. The output magnitude that I chose is fractionally above that of a typical AC-powered source components like a CD player. There are advantages in the resulting signal-to-noise ratio that this higher level provides.

SS: What is your position on asynchronous versus synchronous modes over USB?

KH: The answer to your question requires more than a simple answer as it presumes that there are only two choices. Without giving away too much, let me expand on this just a bit (no pun intended). 

First, a synchronous data transfer can be accomplished in more than one way. By definition, it means that the data rates of the host and client are linked to the same clocking scheme. The simplest is where the host (most often the computer end) provides the clock and the client (the USB-attached device) follows. There is an implication that this is always an inferior method due to the non-real-time operating system used on the host end. Where this presumption falls short is when it fails to recognize that a synchronous system can use other modes of transfer, where the control of the clock is not necessarily the sole domain of the host. 

Second, in an asynchronous transfer, there are multiple clock-generation schemes that can be utilized. There can be any number of buffers on both the host and client end. These buffers can be clocked by a number of different sources. The source of the clocking can be accomplished by a number of different techniques, some of which include things like a recovered and regenerated clock, an autonomous locally generated clock, and varying degrees of mixed schemes. One could also lump the use of an SRC into the asynchronous camp, but this fails to acknowledge that in this approach clock errors are simply exchanged for data errors with little real improvement.

So the simple answer to a not so simple question is that I see validity and applicability to both techniques.

SS: What will be in the Music Streamer Pro? How will it differ from your other products?

KH: The Music Streamer Pro differs from the Music Streamer+ in two main areas. First, it provides a differential (balanced) output, which is supplied on a pair of miniature XLR connectors. Second, the output magnitude (4.5V RMS) is much more typical of what is found in professional audio environments.

SS: Any other plans for High Resolution Technologies products?

KH: Yes, in fact two more products are well into their final development phase, and another is planned after these are in production. Our object is to bring high value and performance products to the market in anticipation of the inevitability of digital distribution of music.


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