You're probably going to struggle during development without a 'scope. And if you don't have a 'scope you probably won't be familar with LTSpice or other simulation suites.
Artificial ground - most audio is AC, AC amplification typically requires split rails (eg +/-5V). You can achieve this by creating an 'artificial' or 'virtual' ground at the mid-point between the single rail and 0V. This might be as simple as potential divider (sometimes with a decent size capacitor(s) across one or both resistors), or it might be buffered by an opamp.
So your +9V and 0V now become +4.5VA (previous+9V), 0VA, -4.5VA (previous 0V), all your circuitry is now referenced to the artificial/virtual ground called 0VA.