A&M/Universal has released Soundgarden’s classic 1994 Superunknown album in the DTS Headphone:X format, which offers 11.1 virtual surround sound through normal stereo headphones.

Is such a thing possible? I am sceptical of the claims for 11.1 (11 discrete channels plus sub-woofer) though the DTS Headphone X demo app is most impressive, and you hear the surround effect clearly. When I first heard this demonstrated at Mobile World Congress in Barcelona, it was so convincing that I took off my headphones to make sure that the sound was not really coming from speakers positioned around the studio.

This demo is included in a new app developed for the 20th anniversary of Superunknown. The app is free. and also includes a free sample track in virtual 11.1, Spoonman.

If you want the full 16 track album in this format, it seems that you have to buy the Super Deluxe box: 4CD plus Blu-Ray at an extravagant price. This includes a voucher which lets you download the full album in the app. Note that the Blu-Ray also includes a 96/24 5.1 surround mix, so you can think of the app as a mobile version of the surround mix, though they are different: the credits say:

Surround sound mixes by Adam Kasper at Studio X, Seattle and Bob DeMaa at DTS, Calabasas, California.

The app offers four settings for listening: In Ear, On Ear, Over Ear, and unprocessed stereo. DTS knows what it is doing: with On Ear headphones, the On Ear setting sounded best and the In Ear setting muffled; with earbuds, the In Ear setting sounded best and the On Ear setting harsh.

But how is the sound? The odd thing about the Headphone X system is that the spectacular demo raises expectations that actual music does not deliver; the surround illusion is less striking.

That said, there is a huge difference in sound between plain stereo and virtual surround. Unfortunately switching to virtual surround significantly raises the volume, making comparison more difficult, but the surround processing does open out the sound and make it more immersive. It is easier to pick out individual instruments. Bass is more accentuated.

It is not all in one direction though; the stereo sounds cleaner and less processed.

Still, I would personally choose to hear the DTS version. It is effective technology even though I cannot honestly say that it sounds like 11.1 surround sound. Producer Kasper is quoted though saying: “The experience Soundgarden’s fans will hear over headphones is identical to how I heard the mix in the studio when producing the surround sound version.” This could be a matter of which headphones you use, or he might be exaggerating.

I am less impressed with the app itself. Tracks are slow to load and I got occasional stuttering on an older iPad. The settings menu pops up repeatedly, rather than remembering your last setting. If you switch from the tracklist to the Player menu and back you get a momentary pause in the sound. The design is basic and it looks as if the app was put together quickly.

It is also obvious that having a separate app for every album is hopeless as a long-term strategy. Space is also an issue. The app with the album downloaded is 344MB and there is no provision for storing the music files anywhere other than in the iPad’s on-board storage. It is unfortunate that once downloaded, the surround mix is only available on that device; you cannot download for both iOS and Android with one voucher.

Overall I still like it, and would like to see more surround mixes released in this format. It may not be quite as good as the real thing, but it is vastly more convenient.

You can get the new app here, on Apple iOS or Android, and try it for yourself.