Pro USB to Pro ISL Adapter


Ultimate isolation. Ultimate performance.
The ProUSB solution is the ultimate solution for computer audio playback. It provides the ease of a USB interface with the added 100% electrical isolation, long cable lengths, data protection and synchronous interface of the MSB ProISL. By using the ProISL interface the source can be located physically far away from the system and a single fiber cable (up to 1km) can connect to the DAC. This removes the need for network cables in the system setup. The advantage of moving the source far away from the system is much lower electrical noise in your listening room.


The input interface can have a significant impact on both the sound quality of the DAC, as well as the overall user experience. Input interfaces are constantly changing and are the main reason why digital equipment becomes obsolete. For this reason, we’ve made our inputs standardized modules that are user replaceable. In each module, we individually design each interface to perform at its absolute peak performance, with minimum noise, jitter, and maximum isolation. While each interface can transfer data to DAC, each has its own advantages and disadvantages. The primary difference between each interface is they add different amounts of noise and jitter to the audio system. With each interface,our goal is to have perfectly isolated, bit-perfect, low noise and low jitter data transfer.

MSB input modules are a standardized, swappable design that supports all of our DACs. This allows any module to be moved from one DAC to another for seemless upgradeability. Each module uses a toolless lever lock system for modules that allows simple, quick upgrades and replacements.

Each interface has advantages and disadvantages.


  • Fully synchronous to the DAC
  • Offers 100% electrical isolation between source and DAC
  • Works with most music server and computer systems that support USB audio
  • Uses the ProISL interface with error correction and detection
  • Virtually limitless in cable lengths (up to 1km) between the USB module and the DAC
  • Works at rates up to 24/768kHz and 8xDSD (with a PC)


  • Offers no control of the DAC from the host source (Volume, etc…)

Key features.

  • 768kHz PCM Playback
  • 8x DSD support*
  • Full MQA decoding*
  • 100% Electrical isolation between the DAC and server/computer
  • Uses the audio clock from the DAC
  • Supports ProISL cable lengths up to 1km without any loss
  • Requires ProISL Input module in the DAC
  • Will only work with current DACs (Discrete, Premier, Reference, and Select)
    *8x DSD and MQA support require firmware updates in the DAC

Multi-part solution.
The Pro USB is one part of a multi-part, low noise USB solution. It converts the USB signal from your computer into MSB’s proven proprietary Pro ISL format. The full connection requires the following:

  • Roon Core / Server / Computer
  • Current generation MSB DAC
  • Pro ISL Input Module
  • Pro ISL cable
  • Pro USB

Pro USB Drivers and Firmware.

Drivers > Click Here

Firmware > Click Here

Pro USB connection setup.
For computer software setup, follow the appropriate guide below:

Roon Setup > Click Here

JRiver Setup > Click Here



Additional information

Weight 0.6 kg
Dimensions 15.24 × 4.95 × 2.23 cm
LED Indications

No Light: No Power
White Pulsing: Standby/No Audio Playing
White Solid: Playing Audio (Format PCM or DSD)
Blue: Playing Audio (Format MQA)
Green: Playing Audio (Format MQA Studio)
Amber: Playing Audio (Format MQL)

USB Connection Format

Type B Powered USB

Power Consumption

USB bus powered, 400mA @ 5V constant draw

Supported Formats

44.1kHz – 705.6kHz PCM Playback
48kHz – 768kHz PCM Playback
1x – 8x DSD support
Full MQA decoding


MSB Technology

Who we are. What we do.

Located in Silicon Valley, our dedicated engineers and production specialists work to bring you the best in high-end audio. Combining elegant design thinking with a passion for lifelike reproduction, our close-knit team, led by brothers Jonathan and Daniel Gullman, build and curate a wide array of hifi products—DACs, transports and amplifiers—setting an industry benchmark. By relying on tight integration between electrical, mechanical and consumer needs, we strive to push the listening experience further. At the end of the day, our joy comes from innovation and sharing our leading-edge technologies with the world.

Designing DACs for more than 25 years has given us keen insights for future ready products. Now, more than ever, our product range has the most flexible architechture yet. California based in-house development and manufacturing has evolved the digital front-end to a new level of playback.

Our people. Our values. Our culture.

We’re a small team of elite designers and technicians united by our love for high-end audio. While we’re builders at heart, our company culture drives the innovation and passion that makes MSB what it is today.

This is who we are.
    • Empower People We rely on a diverse and inclusive work environment where our team is equipped to solve problems on their own—but are invited to seek support when needed.
    • Optimize Quality We promote a culture of growth and improvement that relies upon precision, maintaining high standards and holding ourselves accountable for the work we do.
    • Honest Design We create and support long lasting products while maintaining simple, functional and intelligent design that performs at the highest level.
    • Promote Sustainability We maintain our environmental responsibility by seeking better manufacturing processes and minimizing use of resources.

We believe collaboration leads to excellence. Each member of the MSB team plays a critical role in getting our product out of our doors and into your home.

Contact Us:
    • North America Vince Galbo Sales Manager Phone: (716) 688-3527
    • Europe Very Fine Solutions Frank Vermeylen European Sales Manager Phone: +32 472 42 5775
Find your local dealer > Click Here  
    • MSB Technology Factory & MSB Technology Corp 15 Brennan St. Watsonville CA, 95076 Phone: (831) 662-2800 Hours of operation: Monday – Thursday 8:00am – 5:00pm PST Any questions, email
Need a repair? > Click Here