Moork :
hang-the-9 :
Why not use the sound card outputs? Even new computers have sound card outputs.
No need to use the HDMI output unless you are also trying to send the audio signal to an older TV or monitor without a digital connection.
I wish the solution was that simple. Unfortunately, the computer I want to use is an ASUS tablet, and only has HDMI and earphone jacks.
That's not really a "computer", although technically you can call anything with electronic or even mechanical processing of numbers a "computer". There is a huge difference between tablets and computers.
For the tablet, since the hardware is different, you should talk to ASUS support about what options they have for the sound output to an external speaker system or just do a web search for your model for what's out there. The headphone jack should work also, although you'd lose any surround sound options.