There are two types
The more common one has a DAC built-in, just like the iPhone dongle. Which measures well too.
The Roland one in your link is likely that type.
The other type which is in your other link, those are passive cables. Just wires. And it is normal for you to be confused. These are for specialized equipment, that can actually work with these cables. Some mini MP3 players use the 3.5mm for both analogue audio and USB. Some video equipment use the USB connector to transfer video/audio. There are even things like passive HDMI to VGA cables, or VGA to composite.
The Roland one as quoted on amazon site
This cable is passive, and relies on your computer’s native USB audio support for operation.
So it means USB-to-rca and USB-to-audio jack cables work on Windows ADC-2, right? Then they should work to connect directly from laptop's USB ports to speakers rca ports directly, no?