“The formulation of the problem is often more essential than its solution, which may be merely a matter of mathematical or experimental skill.” – Albert Einstein

Designed to standardize connection with computer peripherals, USB interface enables both communication with peripherals and supply of electric power. Communication with external sound cards (DAC) via USB interface is not really a problem and 480 Mbit/s data transfer speed in USB 2.0 standard is more than sufficient for transport of even the most complex high resolution audio files.

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.

The solution

While other audio companies were busy improving their USB D/A converters, South Korean company SOtM (Soul of the Music) asserted the problem on computer side and the solution practically jumped out.

SOtM tx-USBexp Audiophile PCIe to USB 3.0 card is basically a high end USB port, connected to computer’s motherboard via Peripheral Component Interconnect Express or simply PCIe slot on computer’s motherboard. The card has an ultra low-noise voltage regulator, ultra low jitter clock and can be powered externally with linear PSU or battery. There is also a switch for complete disruption of DC 5V from PC. Simple, elegant and absolutely necessary for high end computer audio transport, SOtM card serves exclusively for connection of USB D/A converters and every single USB DAC connected to PC via SOtM tx USB card will instantly sound better.

Consequently, laptops, Mac Mini, NUC, Raspberry Pi and similar constructions are definitely not able to serve as a State-of-the-Art
computer audio transport.

SotM tx-USBexp card is an ideal link between computer’s motherboard and USB DAC. Therefore, a desktop computer with motherboard that allows connection of at least one PCIe card should be considered as a minimum for a serious computer audio transport. Consequently, laptops, Mac Mini, NUC, Raspberry Pi and similar constructions are definitely not able to serve as a State-of-the-Art computer audio transport.

SOtM card can be swiftly connected to PCIe slot, no experts are required for a really simple installation procedure and only one screw on the back panel of your desktop computer should be tightened.

SOtM USB card can and should always be powered externally, with an appropriate linear PSU or a battery. SOtM recommends the use of a specially developed mBPS-d2s battery power supply for this purpose. We have tested SOtM card with several linear PS units and found out that a non regulated PSU DC 8V works perfect.

Providing clean, noise free power to SOtM USB card makes a real harmonic fireworks. The sound becomes even more involving and completely lifelike. Timbre of acoustic instruments, especially on excellent DSD recordings, is unimaginably sweet and has “organic” character. Actually, there is no going back once you become addicted to sound of externally powered SOtM tx-USBexp card.

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

To make a long story short, computer audio transport via USB interface is simply not possible without SOtM tx-USBexp card, if a true high fidelity is required. A desktop computer with SOtM card is an absolute must for everyone interested in computer audio transport of highest quality. If you enjoy recordings of classical music on period instruments, exceptional DSD recordings of large symphonic orchestra or amazingly recorded, subtle details of jazz trios, a fanless, desktop PC with externally powered SOtM tx USB card is a condicio sine qua non for your future computer audio transport. SOtM card link.

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