I met the company High Resolution Technologies a few years ago through the magazine “Hi-Fi+” then led by Roy Gregory. The devices did not look very impressive, but they gained appreciation not only from the chief editor of HF+, but also from people on the other side of the ocean, where the company comes from. The products of the company are mainly DACs with a single USB input, in which it reminds another American company – Wavelength Audio. There are more similarities – the most important is that USB receiver is asynchronous one. Currently HRT offers four devices of that kind - iStreamer, destined to be used with the iPod, Streamer II, Streamer + and Streamer Pro. They differ in color of the enclosure, and in case of the iStreamer also in shape – those colors are (respectively): light grey, ruby, dark grey and cyan. We test the most expensive model, which costs in Poland 2500 zl. This is a DAC accepting signals up to 24 bits and 96kHz with an asynchronous USB receiver. It has an untypical output – rarely seen miniature balanced sockets TiniQ. It is powered from USB, not needing an external power supply, so we can just connect the USB cable on one side to a computer and on the other to the DAC and we are ready. In the company materials the company asks the USB cable length to be below 5m. Because we do not have a separate power supply my cables Acoustic Revive USB-1.0 SP and PL with separate runs for signal and power will be the best choice. The latter has also a length of exactly 5m.

SOUND

Recordings used in the test (selection):

• Brian Eno, Craft On A Milk Sea, Warp Records, WAV 24/44,1.
• Cassandra Wilson, Silver Pony, Blue Note, 29752, CD;
• Charlie Haden & Antonio Forcione, Heartplay, Naim Label, 24/96 FLAC.
• David Sylvian, Gone To Earth, Virgin/EMI Music Japan, VJCP-68877-78, 2 x CD.
• Diana Krall, From This Moment On, Verve, 1705042, CD.
• Diary of Dreams, Freak Perfum, Accesion-Records, EFA 03647-2, CD.
• Dominic Miller, Fourth Wall, Qrious Music, QRM 108-2, CD;.
• G. F. Haendel, Messiah (Dublin Version, 1742), Dunedin Consort&Players, Linn Records, CKH 312, FLAC 24/88,2;
• George Shearing Quintet with Nancy Wilson, The Swing’s Mutual!, Capitol/Toshiba-EMI, TOCJ-9468, CD.
• Helge Lien Trio Hello Troll, Ozella Music, OZ021CD, FLAC 24/96;
• Stan Getz & Joao Gilberto, Getz/Gilberto, Verve, 24/96 FLAC.

Japanese versions of the discs available at CD Japan.

The DAC from US does exactly what it should: it tries to reproduce that, what is stored in computer memory as precise as possible. We can hear limitations imposed on it by the USB technology in itself, as well as the budget, but those are by far not grave.
The tonal balance is shifted a little upwards. This can be mostly heard with CD quality material, but also with hi-res. When we compare it with the same material played from the Olive O6HD player, then we can hear, that the bass is less saturated.
This because the HRT acts a little like a studio unit – it is true to the music, it shows differences in the setup of the microphones, places where edition was done, etc, in a good, clear way. Its resolution seems good, as is differentiation. We should note however, that this is better audible using 24 bits recordings, than 16 bit ones.
The sound seems also very dynamic. This is an important remark, because music played from file players, and – probably most of all – from computers using the USB bus is usually dynamically flattened, as if it would be compressed. This is of course a subjective description of a physical phenomenon – jitter and high frequency noise produce such results. Streamer Pro does not have big issues with that. This is not the level of a 10000zl DAC, especially in terms of macrodynamics, but for the money, and for playing files from a computer it is surprisingly good.

I mentioned, that the bass is played lighter than in reference devices. This is not the case, that the sound is light or thin. I mean it is slightly thin, but this statement will only be justified, when we compare it with the best CD players, for example with my Lektor Air Ancient Audio, etc, which can be regarded as a kind of master. In such comparison most digital sources fail. So this is a slightly thinned version of the sound, but for the money you will not hear anything else, regardless of the fact, if this will be a USB DAC, a dedicated CD player or a DAC with a signal from an optical drive. And comparing it with for example the Arcam rDAC we can hear, that the Streamer Pro sounds with a disciplined sound, without falling into a romantic mode, but also without thinning it (remembering what I wrote above).
The treble is shown masterfully. There is a lot of it, the upper midrange is also quite strong, but if the recording permits, if the rest of the system will be nice, this will translate into an open, carrying sound. Like I say, treble is good and this because it is clean. The cymbals have a good hit, are vibrant and have nice reverb and air around them.

Interestingly, despite such presentation, when there is a vocal in the recording, then it is promoted in some way, as if the elements in the middle of the sound stage would be a bit better, as if they would be a tad more coherent than those outside the middle line. This got confirmed with the sound stage, but about that in a moment.
All this I am talking about was shown nicely by the disc From This Moment On Diana Krall in the version 24/96 (FLAC), bought at HD Tracks. The same disc played on the Lektor Air had a deeper sound, more velvety, but the Streamer Pro showed Krall’s voice closer, as if it would be pushed more forward, more palpable – better. The same thing was repeated with the disc …Featuring Norah Jones (16/44.1 FLAC and CD) – those tracks with the voice, which were badly compressed, or slightly clipped, were shown closer, and the errors in mastering were slightly underlined. With this disc one could hear best what I told in the very beginning: the American DAC tries to show everything as good as it can, as faithful as it can. More expensive devices handle their interpretation better, HRT shows them rougher.

I mentioned the sound stage. It has two faces. On one hand the most important thing in creating the picture in front of us is that what is on the listening axis. That what is to the sides is slightly, but still, homogenized. I am not sure, if this will be audible on inexpensive systems (probably not), but it was clear in my reference system. For example the recordings from the Jones disc, where she sings in a duo, and the voices are slightly separated, they were for me less palpable, than in recordings with only one voice. The same thing was on the disc Silver Pony Cassandra Wilson (16/44.1 FLAC and CD).
On the other hand, the unit fantastically simulates the space around us, and that, which extends to the sides of the loudspeakers, I mean the elements gained with manipulating the phase (in counterphase). I was enjoying the disc Free Falling Floating.Point, and then the new recordings from Briana Eno from Small Craft On A Milk Sea (24/44.1 WAV). The sounds simulating a city, space, changes in perspective were fantastic – I do not get such a result even from expensive CD players. Also the depth of the recordings was fantastic, underlining the shapes of the instruments on the disc of Milt Jackson and Wes Montgomery Bags Meets Wes! (24/96 FLAC), and on the purist recordings from a copy of the XRCD24 Duet Arimasa Yuki with Hisatsugu Suzuki.

High Resolution Technologies Music Streamer Pro is a small and nicely made device. It was made with one purpose in mind: to integrate a computer with the audio environment, also in a studio. The units fares very well, showing the recordings very faithfully and trying to reproduce as many elements as possible from those that constitute it. Its tonal balance is shifted upwards, but in return we have an open, fresh sound and disciplined bass. A surprise is, that the midrange sounds well – in the studio and studio related gear this is not often the case. Those elements are not so palpable elements as in the reference system, or on vinyl, but they are very good. With regard to the sound stage, then as I wrote, the virtual sources in front of us are strong and big, those to the sides are smaller. But if in a recording we have elements in counterphase, then they are shown brilliantly.
And dynamics, the Achilles heel of many DACs – here it is very good. The volume of the sound, its size is smaller than in the reference devices, but not through worse dynamics, but by the less palpable drawing of the instruments. But when we take into account the price of the unit, then there is nothing to complain about. Good design, good craftsmanship and good sound – a trinity, which should be sufficient recommendation for many of you. It is good!

DESCRIPTION

The HRT (High Resolution Technologies) Music Streamer Pro DAC is a small box with a trapezoidal cross-section. In colorful advertisements in American press it looks bigger, than in reality. In fact I was surprised, how good it looks.
As usual in case of new technologies, there is an issue with terminology. The unit is described in the company materials as “Streaming Audio Interface” and should bring together a computer and the home stereo, or broader home entertainment. This is in some way true, because HRT is an interface. However from a mathematical point of view, this description is not precise enough, because this is a special version of an interface, a DAC. And among the DACs it belongs to the subgroup of DACs with a single USB input. It is worth noticing, that HRT is not following the mainstream with their naming, as usually such products are called USB DACs, what is also not fully correct (Wavelength).

Like I say, the unit is equipped with a single USB input 1.1 (Type B). The power is supplied via the USB cable from the computer. It accepts all PCM based files, meaning AIFF, WAV, FLAC, MP3, etc, up to 24 bits and 96 kHz (32, 44.1, 48, 88.2 and 96 kHz). The unit works with PCs and MACs and does not require special drivers. The USB port is located on one of the sides of the unit; the outputs are on the other side. Those are untypical, balanced, using vey rare, non-standard, but very good TiniQ sockets. When we look how small the panel is, on which they are placed, we can clearly see, why no standard XLRs were used.
It would be best, if we would own interconnects with TiniQ plugs on one side, and XLR on the other. If we do not have such cables, the company supplies suitable converters made by the American company Cardas. I ordered a version with RCA sockets – the Ayon Polaris III preamplifier I use is not balanced. The enclosure is made from aluminum – the front and back from plates, and the whole shell from a rigid cast, and the whole is painted in a nice, light blue color.
The PCB with electronics is inserted into the shell. There are two PCBs – a big one and a smaller one with the USB input, plugged into the larger one with pins. As it turns out, the device uses a Texas Instruments USB receiver TAS1020. This chip works in asynchronous mode (“isochronous asynchronous"). Next to it there is a nice word clock. The DAC is mounted on the main PCB. This is a very good Burr-Brown chip PCM1794 24/192. The output is made based on two ICs OPA1612A (I/V) and two 4131 (amplification and buffering). Although voltage coming from a computer has 5V and is constant, the PCB has three separate voltage stabilizers, the most worked out one for the USB input. This is done because a computer generates a lot of noise, which needs to be lost somewhere.
The sockets are not gold plated, and we need to glue four rubber pads beneath the unit. An interesting detail is the inscription on the main PCB: “In a loving memory of my Mom”.

Technical data (according to manufacturer):
Output voltage: 4.5V (balanced), 2.25V (unbalanced)
Output impedance: 400Ω (balanced), 200Ω (unbalanced); according to “Stereophile” the first one is 198+198Ω
Frequency response: 20Hz -20kHz (0dB/-0.6dB); ”Stereophile” measured the value: –0.8dB at 20kHz with sampling frequency 44. 1kHz and –1.5dB at 40kHz for 96kHz
Noise: 8μV (weighted “A”)
S/N Ratio: 115dB (weighted “A”)
Power consumption: 350mA/5V

Manufacturer:

High Resolution Technologies, LLC, 1027 N
Orange Drive, Los Angeles, CA 90038 USA

tel.: (323) 967-7447
fax.: (323) 466-9825

URL: www.hirestech.com