I use toshiba laptop to hear music from the web. It is connected to an old amplifier. The loudspeakers are in another room in which I use sony laptop, connected with toshiba with ssh -X user@192.168.1.x over home network, for monitoring voice loudness and music source from firefox. The noice of sony's fan disturbes me. I would therefore like to dettache sony and put it in readiness but not stopping toshiba to make music, yet be later able once again to attache to toshiba for monitoring loudness and sources. I tried to use linux screen to dettache and attache remote screen session but was not successful. Has anyone good advice or is it at all possible to run firefox in a linux screen?

When you run firefox in a screen session, it opens firefox to a different output device, separate from your screen session. Yes, it is possible to detach or attach a running screen session, but not the GUI applications that you started.

As for attaching a screen session, I usually ssh into the computer the screen is running on, and then use screen -x or screen -r. ( See the screen documentation for details on options regarding detaching and reattaching screen sessions. )

If you must monitor loudness and voice from a web browser, you could try a console-based browser, one that which would run inside a screen session, such as links, lynx, or 'other'.