Using Raspbian GUI with default user pi might be not fun, but if you decided to create new user, you might have missed setting up polkit configuration to have new user in administrative authentication dialog. Here's my first Raspberry Pi guide to fix it.
Audio line-in is disabled in Linux Mint by default, here is quick solution to unmute this socket.
Quick walkthrough to add more instruments to predefined ZynAddSubFX software synthesizer banks.
Easily check your Linux system for Bash ShellShock vulnerability.
Setting up Sandberg USB Sound Box 7.1 on Linux Mint. Procedure should be similar to any surround sound card installation on Linux using PulseAudio.