An unofficial ASIO driver for the QuantAsylum QA401 audio analyzer.
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ASIO401, the unofficial QA401 ASIO driver

Brought to you by Etienne Dechamps - GitHub

If you are looking for an installer, see the GitHub releases page.


This is an unofficial ASIO audio driver for the QuantAsylum QA401 audio analyzer USB device. This makes it possible to use the QA401 in any audio application that supports ASIO, including third-party audio measurement software (e.g. REW).

DISCLAIMER: while this driver was developed with the help of QuantAsylum (with my thanks to Matt Taylor), it is not officially supported by QuantAsylum. Please direct any support requests to ASIO401, not QuantAsylum.


  • A QA401 audio analyzer USB device
  • Windows Vista or later
  • Compatible with 32-bit and 64-bit ASIO Host Applications


Install ASIO401, then:

  1. Connect the QA401 to your computer.
  2. Open the QuantAsylum Analyzer application.
  3. Wait for the Configuring hardware... message to disappear.
  4. Close the QuantAsylum Analyzer application.
  5. Run your ASIO Host Application. ASIO401 should appear in the ASIO driver list.

You will need to repeat these steps every time you power cycle the QA401.

To disengage the attenuator, and other options, see CONFIGURATION.


The FAQ provides information on how to deal with common issues. Otherwise, ASIO401 provides a number of troubleshooting tools described below.


ASIO401 includes a logging system that describes everything that is happening within the driver in an excruciating amount of detail. It is especially useful for troubleshooting driver initialization failures and other issues.

To enable logging, simply create an empty file (e.g. with Notepad) named ASIO401.log directly under your user directory (e.g. C:\Users\Your Name Here\ASIO401.log). Then restart your ASIO Host Application. ASIO401 will notice the presence of the file and start logging to it.

Note that the contents of the log file are intended for consumption by developers. That said, grave errors should stick out in an obvious way (especially if you look towards the end of the log). If you are having trouble interpreting the contents of the log, feel free to ask for help.

Do not forget to remove the logfile once you're done with it (or move it elsewhere). Indeed, logging slows down ASIO401, which can lead to discontinuities (audio glitches). The logfile can also grow to a very large size over time.

Test program

ASIO401 includes a rudimentary self-test program that can help diagnose issues in some cases. It attempts to emulate what a basic ASIO host application would do in a controlled, easily reproducible environment.

The program is called ASIO401Test.exe and can be found in the x64 (64-bit) or x86 (32-bit) subfolder in the ASIO401 installation folder. It is a console program that should be run from the command line.

It is a good idea to have logging enabled while running the test.

Note that a successful test run does not necessarily mean ASIO401 is not at fault. Indeed it might be that the ASIO host application that you're using is triggering a pathological case in ASIO401. If you suspect that's the case, please feel free to ask for help.

Reporting issues, feedback, feature requests

ASIO401 welcomes feedback. Feel free to file an issue in the GitHub issue tracker, if there isn't one already.

When asking for help, it is strongly recommended to produce a log while the problem is occurring, and attach it to your report. The output of ASIO401Test, along with its log output, might also help.