I mentioned formats earlier, there are many of these to choose from but if sound quality is important then the list gets a lot shorter. The choice is essentially between those that losslessly compress the audio data such as FLAC and Apple’s variant ALAC, and those that do not: WAV, AIFF and more recently DSD. The reason for choosing the lossless formats used to be that they require about half as much storage space, but now that space is so inexpensive that is less valid. What is more important is metadata, all the information about the track including artist, track title, album title, artwork etc. FLAC, ALAC and AIFF all support metadata, which means that if you transfer your music collection to a player that uses different software it will be able to display this key information.
However, WAV is regarded by many to be the best format, it’s not Apple specific like AIFF and it does not compress data, and so long as you stick with the same software the metadata is available. It was the exclusive format of the Naim Unitiserve until last year when FLAC became an option. The thinking today seems to have swung toward FLAC because of its portability and the fact that a good streamer has no difficulty ‘unpacking’ the FLAC container to expand the data within. The fact that high resolution music files are sold in this format is a factor but possibly more significant is that not many people can hear the difference on most streamers. Linn’s position is that there is no audible difference.
On the other side of this fence is that revival of the format that SACD was based on, DSD. A format for which very little mainstream original content is available yet which has become the flavour of the season in the world of DACs. Even Naim has incoprated DSD compatibility in its NAC‑N 272 streaming preamplifier, this despite the fact that the Unitiserve that it sells to complement its streamers is not yet DSD compatible. You can get server software that will stream DSD however, Naim use one called Minim for their dems.
Another approach to streaming hardware is exemplified by the Auralic Aries among a few others, the Aries is a bridge which is essentially a streamer without a DAC. It has USB output for high bit/sample rates as well as S/PDIF outputs on coax and optical. The absence of a converter and analogue output stage makes it less expensive than a high end streamer but theoretically able to compete with such things if you have a serious DAC already. There are not many bridges on the market yet but a high end British example turned up at the Bristol show this year, the Stack Audio Onset with its dCS style casework looks very promising.
As well as providing easy access to your own music collection a streamer also opens up the world of internet radio and streaming services. There are seemingly millions of net radio stations around the world that can be searched for by region or genre, and many can only be accessed online. If you are looking for niche programming there is no easier way to find it and while sound quality is variable it’s not a lot worse than other digital broadcasting. In some cases companies get exclusive access to higher quality streams, Naim streamers provide both Naim Radio and Radio Paradise at 320kbps for instance.
Streaming services are more like an online library from which you can pick and mix tracks, albums and artists. For sheer breadth of catalogue it’s hard to beat Spotify but that is limited to 320kbps on its £10/month premium service or 128kbps otherwise. There are two services that offer CD quality streaming, these are Quboz from France and Tidal. The catalogues from both are large and growing, but not in the Spotify league yet, and don’t include certain major artists, the Beatles are not represented and neither are artists on the ECM label which is perhaps more pertinent. Quboz has a considerably larger classical library of the two and offers a 15‑day free trial, Tidal’s is only seven days unless you can pick up a voucher at a show. Both services cost £20 a month and sound quality is pretty good, not up with your own library but good enough to enjoy on a decent system.
Since this feature was written, Apple has announced its own upcoming Music service.
Streaming has not quite scaled the sonic heights of the best analogue and digital sources and being a young technology in audio terms there is room for improvement in the software provided by some companies. That said it is 21st century audio technology that doesn’t cost a fortune. I use streaming for the majority of my reviewing work, it doesn’t sound as good as my turntable but it’s pretty damn fine and a whole lot more user friendly.