The “audio playback is not supported by your sound card” message may be shown when you are attempting to play back high-quality audio files that have been stored by the Optimus/Optimus+ Green sound level meter or the Trojan noise nuisance recorder.
This can happen when trying to play studio-quality audio on older computers or with certain built-in sound cards. The sample rate and bit depth of studio-quality recordings are 96kHz and 32bits, and sound cards in older PCs often do not support these high-fidelity formats.
The solution to this is to either upgrade the sound card inside the PC or to use an external sound card that can support this type of file.