Asus has prepared an impressive sound offering including the PCI-Express x1 version of the Xonar D2 soundcard, along with better DirectSound, EAX and updated drivers for the Windows Vista users. Although there are a few changes in style when compared to the previous D2 version, the PCI-Express model will bring quite a few surprises, as described below.

The D2X version features the same EMI shield and illuminated parts as the D2 model. The Dolby and DTS features are the same, too, but what makes this sound card special is the ASIO 2.0 support that can bypass the OS kernel in order to provide an extremely low latency direct sound communication.

Another important feature is the presence of the ALT sound, that enhances access to Digital Rights Management (DRM) -free audio. This option sets the digital audio free from any restrictions once it has been decoded and passed to the analogue hardware. The same ALT hardware can re-convert the audio signal back to its original, digital form, while stripping it from all its DRM restrictions.

The conversion is done while preserving the quality of the MP3 file. Asustek makes sure that you know this is a legal method of circumventing the digital rights management restrictions, as there is no cracking involved into the process. However, this option is available to allow the user to back up the original music files in any desired format.

The central piece in the ALT technology is the Asus Portable Media Processor (PMP), which also gives the user the possibility of adding extra sound effects like Dolby Headphone or Dolby Virtual Speaker to the cloned audio files. Unfortunately, the software only works while playing the file at a normal, 1:1 rate. In order to get an album backed up, you will have to listen to it from the first track to the last.

Apart from the Xonar D2X model, the only PCI-express card is the Creative X-Fi Xtreme Audio, a low-budget solution that sells for about $57. If you would like to use a professional PCI-Express soundcard, the only option is The D2X. Although the soundcard has been announced for a long time, it is not available through the retailers' stores yet. When it finally gets widely available, its price is estimated to vary around $219.