Poor input sound

[araf22]

I've recently upgraded my system to a Lenovo PC running Windows 10. On the old system I could record from external audio devices by connecting the headphone socket on my amplifier to the audio input socket on the PC, but when I do this on the new setup I get very poor distorted sound.
Device manager shows that I have two sound cards: AMD High Definition and Realtek High Definition. If I disable AMD there's no difference to the sound quality; if I disable Realtek I don't get any input sound at all.
Can anyone suggest what's causing the problem and how it can be fixed?
Thank you.

 

[Trouble]

Are you currently running the R2.79 2015/6/25 from here http://www.realtek.com.tw/downloads...=24&Level=4&Conn=3&DownTypeID=3&GetDown=false

 

[araf22]

Are you currently running the R2.79 2015/6/25 from here http://www.realtek.com.tw/downloads...=24&Level=4&Conn=3&DownTypeID=3&GetDown=false

I wasn't, but I've downloaded it and there's a great improvement - thanks very much.
However, Device Manager now shows that I am running two, apparently identical Microphone (High Definition Audio Devices), both Realtek. Should I uninstall one of them?

 

[araf22]

After a reboot it's gone completely haywire - here's a clip of what I'm getting.