Youtube video: HRT MicroStreamer DAC-plus-Headphone-Amp review by Dale - YouTube When I connected the HRT MicroStreamer to my PC and Mac computers I was pleasantly surprised that it interfaced perfectly with no configuration effort. The MicroStreamer is a very small USB device with a mini-USB jack on one end and two 3.5 mm jacks for headphone and Line Out on the other end. I confirmed that the Line Out jack delivers the same signal (audibly) as the headphone jack when the computer and music player volume are set to their respective maximums. With this "repurposed" digital volume control, where the system volume is actually taken over by the DAC so that decreasing the volume doesn't compromise audio quality, it's generally advised to keep the music player volume at maximum and use the system volume slider only. HRT supplies a 19-inch USB cable with the MicroStreamer, which I replaced with a 12-inch cable. Since the asynchronous DAC re-syncs the bits after they arrive at the DAC, I assume a short USB cable should suffice to preclude any cable-induced losses. On the other hand, when using the Line Out jack to feed the DAC's analog output to a headphone amp or power amp that has its own volume control, that interconnect cable should be as high in quality and as short as possible. The key feature that distinguishes this mini-DAC from other audio devices that perform the same function is having a DAC and headphone amp** together in one little plug-in device. For people who have been using the headphone jack on their desktop or laptop computers, and assuming that those computers have USB ports, they should expect better sound using the MicroStreamer instead of the computer's headphone jack. The actual improvement with my computers is a cleaner sound with a greater sense of "space" and "air" around the instruments. The tiny size for what it does may suggest to some audiophiles that the MicroStreamer's sound would be of much less quality than the typically separate DACs and headphone amps selling for a much higher price. My feeling is that for good quality computer audio played on the typical dynamic headphones that will be used with a small DAC/amp like this, the sound quality of the MicroStreamer is more than adequate. **While I don't have the original text in hand, I recall a designer of one of the first mini-DACs (HeadStreamer, DragonFly et al) stating that the mini-DAC does not contain a headphone amp per se, but that it provides a variable-volume signal sufficient to drive an average dynamic headphone. Performing comparisons today with the MicroStreamer and AudioQuest DragonFly mini-DACs, playing a variety of 96 khz music tracks downloaded from the HDTracks and DownloadsNow sites, the main difference I hear is a smoother sound from the MicroStreamer, as though there were greater detail with less distortion, or conversely some rounding off of transients as one might expect with a valve/tube amplifier. It might be possible to pin those differences down to measurable performance data, but I've seen instances where measurements say one thing and expert ears (not mine) say something different, so I'll leave it go at the impression of smoothness and better musical detail, and someone else can determine whether it really sounds better or certain problems are being masked by the device's limitations in absolute accuracy. When I performed listening tests of the HRT HeadStreamer, Audioengine D1, and AudioQuest DragonFly mini-DACs a few months ago, I found very little difference in their sound, and concluded that the differences weren't significant for music playback on those devices using mid-priced dynamic headphones. Since then I've looked at two new mini-DACs - the Meridian Explorer and the HRT MicroStreamer. If I had information that suggested the Explorer might sound significantly better than the MicroStreamer, I would have held off on purchasing the MicroStreamer until I was more certain of the differences. As it turned out, I got the idea that the MicroStreamer might be as good as the Explorer in the main despite the lower cost, so I went ahead and bought the MicroStreamer. If it turns out that the MicroStreamer is rated lower in sound quality than the Explorer by trusted reviewers, I won't be disappointed since the sound I'm hearing from the MicroStreamer is excellent, and a good value for what I paid. Questions have come up as to whether a typical computer's USB port can supply enough power to run the MicroStreamer's DAC and headphone amp, to provide good volume especially in the bass where the greatest power demands occur, and to have enough headroom to avoid clipping or otherwise distorting the loudest most dynamic music passages. The answer is a qualified yes, since I have many FLAC format music tracks with a 96 khz data rate that have extreme dynamics which distort noticeably when sufficient power is not available, and all of those (so far!) play loudly enough on the MicroStreamer. The headphones I've tested the MicroStreamer with are the ATH ESW11-LTD, Soundmagic HP200, and Beyer DT770LE. There were a few tracks where I had the computer volume at maximum with the DT770LE, but that headphone does have a lower efficiency than the 32 ohm rating indicates. Still, caution is advised since I expect that many headphones won't play loudly enough with the MicroStreamer with some music tracks. The MicroStreamer is a 63 x 30 x 11 mm aluminum box with the ports on either end as noted above, and with LEDs on the side for 32, 44, 48, 88, and 96 khz sample rates. It comes in a tiny cardboard box with a 19-inch USB cable and a very thin "bag" that presumably would hold the MicroStreamer and the cable, for carrying around in a computer bag or backpack. I'd suggest a better more protective case, such as Case Logic makes for carrying various memory cards or very small digital cameras.