Downloaded music, mostly lossy mp3s, is easily enjoyed on portable 
                  devices and PCs, but these will be found wanting when it comes 
                  to high-resolution audio files. The latter, typically 24bit/96kHz 
                  but sometimes 24/192, are beyond the capability of off-the-shelf 
                  players and computers. However, if you listen to music on your 
                  PC a suitable sound card - such as the ASUS Xonar Essence ST 
                  or STX - is one option. I use the ST on a Windows 7 PC and I 
                  can vouch for its audio credentials. Indeed, in their original 
                  review Stereophile magazine described it as a true audiophile 
                  product. At around £140 from Amazon it really is a steal, 
                  especially as it can handle 24/192 files. 
                    
                  But if you don’t want to go that route there are a number 
                  of portable digital-to-analogue converters (DACs) that will 
                  do just as well. Perhaps the best known is the Cambridge 
                  Audio DacMagic Plus, which can be linked to your Mac/PC 
                  in a number of ways. It also offers a headphone socket and volume 
                  control, so that should broaden its appeal. And then there’s 
                  the much cheaper HRT HeadStreamer, a USB-only device that’s 
                  small, light and capable of handling 24/96 files. As it’s 
                  an asynchronous USB design it bypasses the Mac or PC’s 
                  sound card and requires no special drivers. It’s also 
                  bus powered, so it dispenses with fiddly power cords; that makes 
                  it ideal for music on the move. 
                    
                  The HeadStreamer may be small, but don’t be fooled by 
                  its size. It arrives in a plain box with a drawstring pouch 
                  and a short standard USB to mini-USB connector. The front plate 
                  has a series of LEDs that indicate the selected resolution, 
                  from 32k to 96k, and whether the device has been muted. There’s 
                  a 3.5mm headphone jack on the right and a mini-USB jack on the 
                  left. I would have preferred the latter to be on the back, but 
                  it’s hardly a deal breaker. And if you’re so minded 
                  you can upgrade to a better USB cable, although not everyone 
                  would agree that’s a change worth making. 
                    
                  I plugged the HeadStreamer into my iMac and using the Audio 
                  MIDI Setup pane set the default audio output to 24/96. Immediately 
                  the 96k LED lit up, indicating the device was primed and ready 
                  to go. Now since iTunes doesn’t support flacs - the chosen 
                  file format for most high-res downloads - you’ll need 
                  to install a media player such as Songbird, which does. That 
                  said, Chandos and Linn are two labels that offer files in other 
                  formats, so iTunes should cope with them easily enough. I’m 
                  sure it’s just as straightforward if you’re using 
                  a PC and Windows Media Player. 
                    
                  So how does it sound? Rather good is the short answer. It’s 
                  certainly streets ahead of the iMac’s very basic audio 
                  card. That said, your choice of headphones will be crucial. 
                  I experimented with my trusty Sennheiser HD600s (impedance 600 
                  ohms) and, not surprisingly, the HeadStreamer struggled to drive 
                  them. That changed with a pair of ‘phones designed for 
                  portable use - in this case the foldable Sennheiser PX 100s. 
                  Already a surprisingly accomplished set of cans the little Senns 
                  really sing with the HeadStreamer; bass is firm and reasonably 
                  extended, the mids are expressive and the treble is free of 
                  hardness or glare. 
                    
                  As always, it all comes down to the quality of the incoming 
                  data. Lossy mp3s sound okay, but feed this little gem with a 
                  24/96 Studio Master from Linn/Universal - I’ve reviewed 
                  several of them for Download Roundup - and the big, broad soundstage 
                  is astonishing. I used this setup when I auditioned Wigglesworth’s 
                  new Shostakovich recording - downloaded from eclassical.com 
                  - and was impressed with the results (review). 
                  That said, the HeadStreamer/PCX 100 combination is a little 
                  overstretched by the huge dynamic swings of Fuga’s organ 
                  CDs, played via iTunes. But as I write I’m listening to 
                  something more intimate - Fischer-Dieskau’s Schöne 
                  Müllerin - and it’s effortlessly detailed and 
                  fatigue-free. In fact, just about everything sounds good on 
                  this Goliath of a gadget; Noseda’s new CD of Britten’s 
                  War Requiem (LSO Live) has plenty of impact and, where 
                  appropriate, great subtlety. 
                    
                  The HeadStreamer’s quirky design won’t please everyone, 
                  but it’s very well screwed together and it excels where 
                  it matters - with its sound. Portable DACs are getting better 
                  all the time - and cheaper - but for now the HRT HeadStreamer 
                  is a cracking performer, ideal for headphone listeners who want 
                  high-res music from their home PCs or on the move. 
                    
                  Dan Morgan
                  http://twitter.com/mahlerei