I was playing with my Rigol Oscilloscope to measure my laptop power output. The sound card was Realtek ALC660.
I played a 1 kHz sine wave with a software and measure the output. Since this was not an isolated environment (I have some application running on the background), so the frequency measured was not completely locked at 1 kHz.
On my typical daily usage, the output measured at 102 mV.
I cranked up everything to maximum to see how loud the output is. My oscilloscope detected around 1.22 Volt clean output. This was quite nice and adequate for most application.
We will check some other sound card later, while I also needed to improve my oscilloscope usage skill.