Thank you for your questions.
For software versions before 3.6.0.4, IMD measurement requires the signal generator of the software to generate a multi-tone signal consisting of two test frequencies. If the generated signal is mono, then only the IMD of Channel A is measured. If the generated signal is stereo, then the IMDs of both channels are measured. For DSO-2810, the generated signal is mono.
In the latest version (V3.6.0.4), the above restriction has been removed. Now, IMD can be measured even if the signal generator is not running, therefore an audio CD containing the IMD test tones can also be used in IMD tests instead of the software's signal generator. The software will detect the two IMD test frequencies automatically. You can download the latest version at:
www.virtins.com/MIsetup.exe .