This technology provides a simple, yet comprehensive, high resolution audio solution for computer audio users. With bit-transparent audio streaming at 96 kHz, 24-bit, Benchmark's Advanced USB Audio solution is a dream-come-true for lovers of high quality audio playback. Enjoy phenominal levels of resolution from your computer within seconds of connecting the USB port. Benchmark's USB technology is compatible with virtually all audio applications and has been extensively tested on four operating systems (Microsoft® Vista, XP, 2000, and Mac OSX).
Benchmark Media Systems has the distinction of presenting the first native, 96-kHz, 24-bit USB audio solution. By intelligently using the capabilities built into the Windows and Mac operating systems, this technology enables bit-transparent audio streams at resolutions up to 96 kHz, 24-bit, when all other native solutions are limited to 44.1-48-kHz, 16-bit. Thus, the fidelity that was originally captured in the recording can be fully appreciated.
There is no need to configure and re- configure software to ensure proper bit-rate settings. With this advanced technology, high-resolution audio is automatically passed from the source program to the USB without data modification.
A digital audio path can be tested to determine if the digital data is being modified or distorted in any way. This is done by sending a random sequence of bits through the path, and comparing the resulting sequence with the original sequence. If the resulting sequence is always identical to the original, the path is 'bit- transparent'. Benchmark's Advanced USB Audio Technology is the first native USB solution capable of streaming 96 kHz, 24-bit audio with full 'bit-transparency'.
Until now, high-resolution USB audio devices required 'custom' drivers. These drivers may compromise the stability of the operating system, and may cause conflicts with other installed devices. In addition, custom drivers usually consume more system resources (memory and CPU) than native solutions.
It is also interesting that many of the ASIO high-resolution USB devices we tested failed to deliver bit-transparent audio. In contrast, many of the native USB audio devices delivered bit-transparent audio. Our tests show that custom drivers do not guarantee bit-transparent data transfers, and that bit- transparency can be achieved without custom drivers.
The problem with native USB audio devices has been their inability to stream audio at sample-rates over 48 kHz and at word- lengths over 16-bits. Benchmark's Advanced USB Audio technology extends bit- transparent native USB audio to resolutions up to and including 96 kHz, 24-bits.
A common problem with streaming audio via USB is the presence of pops and clicks. Audio requires constant un-interrupted data flow. Any gaps in the audio data will cause clicks and pops if buffers are not working properly. The Benchmark Advanced USB Audio solution was engineered to establish and maintain a properly buffered un-interrupted flow of high resolution audio data.
Benchmark's Advanced USB Audio technology is truly 'Plug and Play'. When connecting to a USB port on a computer running Windows® 2000, XP, Vista, or Mac OSX, the computer will automatically and instantaneously recognize the presence of the Benchmark USB device. Any audio played from the computer will then be routed to the Benchmark USB device immediately. There is no software to install or configure.
Most devices with custom drivers only connect to one application at a time. This is especially true with devices using ASIO drivers with Windows operating systems. The device will 'lock' to a specific audio application, leaving all other applications unable to access the device. Benchmark's Advanced USB Audio technology allows as many applications to access the device as needed. This convenience allows the user to switch between a music player to a video player or web-streaming player without needing to reconfigure any software or hardware.
Windows® 2000 and XP operating systems have a digital mixer known as 'Kmixer'. All audio streams must go through the Windows® Kmixer to reach native USB audio devices. The performance of Kmixer is critical to any native USB audio solution, so we tested it extensively.
We found that Kmixer can perform with full or near full bit-transparency under the right conditions. But, under the wrong conditions, Kmixer can do a great deal of damage.
Kmixer's sample-rate-conversion is of very poor quality (under XP and 2000) and must be avoided. Benchmark's Advance USB Audio solution allows Kmixer to default to a transparent mode of operation that avoids sample rate conversion.
In contrast, sample-rate-conversion is outstanding in Vista. By default, Vista up- samples to the highest sample rate supported by the connected audio device. This up- sampling is so well designed that it should not be capable of generating audible artifacts. Nevertheless, if true bit-transparent operation is desired, Vista.s sample rate conversion can be tuned of by manually setting the system sample rate.
In any Windows® operating system, true bit- transparency is only achieved when the 'Wave' volume control is set to maximum. Nevertheless, we discovered that the Windows® volume controls are very well executed and are distortion-free when streaming to a 24-bit output device.
Whenever audio is originating from a single application, Benchmark's Advanced USB Audio solution prevents Kmixer's sample- rate-conversion so that bit-transparency can be maintained. It also forces Kmixer into a 24-bit output mode so that the Windows® volume control does not degrade the audio quality if it is used.
Benchmark's Advanced USB Audio solution offers users the convenience of simultaneous high-quality playback from more than one Windows® application. Kmixer's sample- rate-conversion is disabled as long as all applications are playing files at identical sample rates. If the sample rates do not match, sample-rate conversion is only applied to the lower sample rates, and the high sample rate signals remain at high- quality.
The system sample rate must be set to match the sample rate of the files being played, and the system volume control must be set to 100%.
Like the Windows® XP and 2000 operating systems, OS X has very poor-quality sample- rate-conversion. The system sample rate is manually set and must be set to match the sample rate of the audio being played. This is not a problem if the system will always be used at a single sample rate such as CD.s at 44.1 kHz.
OS X also has a poor quality master volume control. It will degrade the quality of the audio if it is not set to 100%. Fortunately it is bit-transparent when set to 100%.
OS X is capable of bit-transparent audio playback when the system sample rate is set to match the audio, and the system volume control is set to 100%.