The SOtM tX-USBexp is an advanced audiophile PCIe to USB 3.0 interface like no other. SOtM has designed this card to provide a USB 3.0 port with the highest possible power and signalling quality so that an external USB DAC audio card can be connected to a PC without the ‘dirty’ power and data lines from the PC in any way affecting the purity of the audio quality from the DAC unit. By using noise filters and other isolation and electrical improvement circuitry, the SOtM USB card will allow the audio quality of your USB DAC to really shine through. If you have a DAC which doesn’t need USB power, a switch on the card can be moved to the off position which will stop any power being sent from the PC to the DAC.

The card has a unique design incorporating a new and improved ULNR (ultra low noise regulator) for digital signalling, clock and USB power circuitry. It has power input noise filters, PCI Express slot noise filters, an extremely low jitter clock and an active noise canceller for clock power. 

The problem

Powered by incredibly noisy and for computer audio completely inappropriate 5V DC, USB interface is an excellent connection for various PC peripherals like printers, external hard drives, keyboards, mouses, digital cameras etc. However, an extremely power sensitive D/A converter shouldn’t be connected to, or even worse powered by 5V generated from motherboard’s switching power supplies. Tragically, some USB converters cannot even be recognized by computer, if 5V from motherboard failed to reach their USB receiver.

High quality USB D/A converters require high quality USB port

The problem of high end audio gear connection was not considered during development of USB industry standard and therefore optimal conditions for this type of peripherals cannot be expected. Furthermore, connecting of other USB devices to the computer used for audio transport, particularly USB disks or even a mouse can seriously affect the quality of audio playback. High quality USB D/A converters require high quality USB port, separated from other USB devices, dedicated to audio transport only and there is, unfortunately, no such a thing on computer motherboards.

Computer audio transport via USB interface is simply not possible without SOtM tx-USBexp card, if a true high fidelity is required