Getting an I/O device is pricey.
If you have a headphone/speaker output on your laptop, the results will be the same with a "Y" type splitter. The splitter plugs to the output of your laptop and the 2 female ends are 1 for the headphones and 1 for the speaker amp inputs.
In this way you can adjust the volume for the headphones.
Now if your speakers are self amplified, then you can adjust the volume controls on them. Same applies with a stereo amp.
If there's one thing I learned in the electronics industry, is K.I.S.S. = "Keep It Simple Silly".