The SXD2 is fully compliant with USB 1.1 specification and utilises ‘Full Speed’ (12Mbps) transceivers. The bandwidth offered by ‘Full Speed’ USB is more than sufficient to stream digital audio.
Designed to bypass the inherently flawed soundcards internal to computers, the SXD2 offers plug and play convenience when connected via the USB port.
RCA connectors are inherently disadvantaged for use with the high frequency (1.4MHz-2.8MHz) signals associated with 44.1kHz/16-bit digital audio. Design limitations mean RCA connectors can never achieve a characteristic impedance of 75H, resulting in reflections and signal loss due to impedance mismatch. In contrast, BNC connectors are purposely designed to carry high frequency signals, up to 2GHz for 75H – therefore overcome the problems exhibited by RCA connectors.
The SXD2 automatically up-samples the digital signal 4x the input sample frequency, up to a maximum of 192kHz. For example, if the digital input is 44.1kHz (CD), the SXD2 will up- sample to 176.4kHz (4x 44.1kHz).
Rather than offer constant up-sampling to 192kHz, we have purposely decided to use a multiple of the input frequency (4x). This guarantees that every 4th sample will be true. Using 44.1kHz sample frequency as an example, if it were up-sampled to 192kHz, then only every 640th sample would be true to the original 44.1kHz signal.
Red Book Audio CDs have a sampling rate of 44.1kHz and 16- bit resolution. This results in a maximum possible Signal-to- Noise Ratio (SNR) of around 96dB. Increasing the resolution to 24-bit not only reduces quantization error in signal amplitude, but also increases the maximum possible SNR to around 144dB.
