sounding off - bad noises
I am having some issues with the audio output from my favourite desktop computer. Normally, the sound out is very smooth and nice on the ear. When the machine is first turned on there is a bit of hiss and wooshing, not loud but noticeable, this goes away once the OS (Linux Mint 18.x) is up and running and noises from all applications and media players is good to listen to. This last few days I have found that the hiss and whoosh doesn't go away when the OS is established and on top of that there is an additional buzzing noise related to all movements of the mouse and keyboard actions. When listening to music via Youtube the sound quality has become very harsh and gritty, not at all nice to listen to.
The machine has not got any internal speakers, all of the sound is piped to a decent HiFi power amplifier and some good sized speakers.
My first thought is that I am having an issue with my graphics card, which has the sound output stuff associated with it. I have tried using an external sound card jobby that plugs into a USB socket, the sound issues are pretty much the same as the graphics card ones.
I don't know what to try next.
Anyone?
Thanks,
Rans6........................................