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HRT HeadStreamer Review
Introduction
The HeadStreamer by High Resolution Technologies (HRT) is a USB DAC/Amp combo device. It has one USB input and one 1/8" stereo output. The USB input accepts up to 24-bit 96 kHz audio. The device is powered from USB and has no external power adapter. It retails for $140.
The most striking feature of the device is its use of the asynchronous transfer mode over USB. The HeadStreamer is the most affordable USB DAC that includes asynchronous mode as far as I know. Asynchronous mode allows the DAC to decide when data should be sent over the USB connection using its own high-precision clock. This greatly improves the sound quality by removing many timing-related distortions in the audio signal.
Another interesting feature is when you adjust the volume in Windows, it controls an analog attenuator inside the HeadStreamer. It avoids digital attenuation which can cause a loss of resolution.
Packaging
The Headstreamer comes in a white cardboard box, wrapped in bubble wrap along with a white micro-USB cable. It comes in a protective black felt bag with a drawstring.
Build
The Headstreamer has a metal enclosure with plastic end pieces secured by screws. The PCB slides in and out of the enclosure. The case and the end pieces have a "rough" texture to them. The USB and headphone ports are attached directly to the PCB, so there is no possibility of loose wires inside the case. It has a manageable weight that's not too light, not too heavy.
Pictures
Parts
Inside, we can see that HRT has decided to use the TI TAS1020B for USB transfer. Basically, it is a programmable controller that supports asynchronous data transfer over USB 1.1.
There also seems to be a 6 MHz crystal oscillator on board.
For the DAC, HRT has chosen the TI PCM1793, a fairly high-end DAC chip.
Headphone output is handled by two Burr Brown OPA 2132 opamps.
Installation
Installing the Headstreamer was as simple as plugging it in to the USB port on my laptop running Windows 7 Home Premium. The device was immediately recognized as "Headstreamer" and the drivers were automatically installed. It was also automatically set as the default audio device.
Setup
My preferred media player is StealthAudioPlayer 0.22, which uses WASAPI "Pro Audio" mode and can handle FLAC files. All files used for listening tests were FLAC encoded. I tested the Headstreamer using Phonak Audeo earbuds and modified Sennheiser HD580 headphones.
The listening notes below are based on the HD580 because I could detect no significant differences between the Headstreamer and my laptop's headphone jack when using the Phonaks. However, there were significant differences when using the Sennheisers. For all tests I set the volume at 60 in Windows which automatically adjusts the analog attenuator in the HeadStreamer. I would say most people would not go above 70. However, even 100, while it would probably cause ear damage, is not as loud as it would be on other headphones with a lower impedance. The Sennheisers are 300 ohms.
Listening Notes
Ottmar Liebert - UnderWorld (from album "Up Close," 24-bit 96 kHz Binaural)
Wow. I actually forgot I was wearing headphones for this track. There is a guy slapping a pot to the right of me. I can also hear the breathing of the guitarist. There are two guitars on this track, they both appear on the soundstage as completely separate points of sound. The soundstage is wide, but it feels like I am in a small room. Every instrument is reproduced distinctly and with realistic texture - guitars, bass, drums. I would rate this a 7.5/10 on the scale of "how close to reality" the recording is.
Soundgarden - Black Hole Sun (from album "Superunknown," 16-bit 44.1 kHz)
Guitars are pretty crunchy on this track. The best part of this track for me is Chris Cornell's vocals. I can really sense the depth in his voice. The bass frequencies from the drums are very well-defined, but not very impactful. I think this has to do with the frequency response of the Sennheisers. Soundstaging is more deep that it is wide. I can detect several layers of instruments. Drums, then guitar, then vocals behind. Even in very congested parts of the track every instrument is distinguishable. The resolution and detail is very good - this is most evident with the cymbals. The vocals are never grating.
Smashing Pumpkins - Bullet with Butterfly Wings (from "Rotten Apples," 16-bit 44.1 kHz)
First thing I notice is Billy Corgan's voice seems a little artificially compressed. I never would have noticed this with a less revealing source. The guitars sound amazing on this track. The drums and bass are very deep yet crisp, and together create a ambience that involves you in the music. The vocals are always on the edge of being grating, but the HeadStreamer/Sennheiser combo is able to keep them just energetic and not over the edge to painful. This is my favorite song.
Mumford and Sons - The Cave (from "Sigh No More," 16-bit 44.1 kHz)
Guitar is clear and detailed with great realism. After the first few lines of the song the sound changes subtly - the guitar is pushed into the background. The vocal is clear and crisp, with great depth and texture. There are a lot of very congested passages which are handled perfectly by the HeadStreamer - 5 or more instruments playing at the same time and all of them are distinct with full detail intact. Not a big soundstage on this track.
Tinariwen - Le Chant Des Fauves (from "The Radio Tisdas Sessions," 16-bit 44.1 kHz)
This track really shows off the bass frequency capabilities of the HeadStreamer. Even with the bass roll-off of the Sennheisers, the drums in this track are deep, controlled, perfectly timed and powerful. Overall the drums are very pleasantly rendered. They are hand drums, and every strike is reproduced with exacting detail. Guitar is fine, but not very exciting. Vocals are okay, but the effects of amplification (on the recording side) can be be clearly heard. The resolution of the this setup leaves me wanting a more realistic recordings.
Alicia Keys - If I Ain't Got You (16-bit 44.1 kHz)
Piano is 6.5/10 in realism. Can hear the reverb in Alicia's voice. The layering of the piano/guitar/vocal/drums is very clear and distinct. The upper range of Alicia's voice is very nicely rendered, again without grating or sibilance, unlike my laptop's audio jack.
Conclusion
The HeadStreamer clearly reveals the flaws of recordings that are not perfect. At the same time, for well-recorded material like the Ottmar Liebert HD binaural track it can deliver a true virtual-reality experience. My listening session leaves me wanting to upgrade my headphones (DT-880 600 ohm) and find a dependable source for 24/96 quality recordings.
While in absolute terms there are definitely tweaks and upgrades (maybe LM4562 instead of OPA2132?) that can be done to turn this device into a true giant-killer, in comparison to other devices in its price range I really do not see an alternative with the same level of sophistication in design. As part of the "first generation" of affordable asynchronous USB audio devices, the HeadStreamer stands out as an affordable, great-sounding device that will probably stand the test of time.
The HeadStreamer also has the same USB interface and DAC as HRT's other product, the Music Streamer II. I suspect that people with high-impedance headphones can opt for the Music Streamer II and an external amplifier for more voltage swing, albeit at a higher cost than the all-in-one HeadStreamer.
Rating
Features 7/10
Packaging/Build Quality 6.5/10
Ease of Setup 10/10
Sound Quality 9/10
Value 8.5/10
. One question. One (only as of now) review in Amazon mentions that treble is a bit hot. Do you also feel like that?
