Fortunately, there is a workaround to fix this problem and we share it with the players.
For Windows/Linux
So, in order for the sound in the game play-cs.com to become "divinely" pure on Windows 10 (and other editions, up to Windows 7), you need to do:
1. Enter the sound settings: All settings -> Sound -> Sound Control Panel
2. Choose your sound output device in the tab Playback and go to the tab Advanced
3. Set Default Format в 16 bit, 44100 Hz (CD Quality)

Unfortunately, after that, clicks may appear in the standard Windows sound scheme, so we recommend disabling standard sounds in the settings: All settings -> Sound -> Sound Control Panel -> Sounds -> Sound Scheme

After performing these simple steps, you will get a comfortable game sound in your headphones or speakers.
Linux users (tested on Kubuntu 19.10).
For MacBook
The problem of crackling-hissing sound in the game on the MacBook 16inch 2019 is solved like a solution for Windows.
Open Applications/Utilities/Audio MIDI Setup
We change the frequency for headphones and internal speakers from 48000 to 44100.
The sound is also normal if you install 88200 or 96000, maybe 44100 will not be enough for someone.
By changing the frequency, restart the browser.

Stay tuned!