I have a line level input connected to the line in jack on an Aspire 8930 laptop running Windows 7 x64 (Ultimate) (Realtek built-in audio). The Sound applet, Recording tab, shows a suitable audio input level and I am able to record using any audio software and playback the recording just fine. I can monitor the input on the same audio device (built-in laptop speakers).
Up until very recently I was able to use the 'Listen to this device' option on the Listen tab of the Line In properties and choose a 'playback through this device' output option that differed than the Realtek device itself (I have a Jabra headset and a Sennheiser audio device that I have connected to speakers, both are connected to the laptop via USB). I was able to listen to the input audio on either device as selected without issue.
I discovered today that this no longer works. Signal is there, I can record and see it. But the audio can't be heard, no matter what device I choose. Outputs are working fine (I can listen to music, hear them 'ding' as I adjust volume, etc.).
I've worked around it for the moment using the virtual audio cable trial, audio repeater utility. Chose both the input and output devices and can listen to it fine.
Note that the problem doesn't seem to be isolated to the Realtek audio card. I used the Sennheiser input rather than the Realtek line in and experienced the same issue - the LIsten to this device feature did not work.
I'd like to know what went wrong. Any help would be appreciated - thanks.