Room modes: Slow sine sweep 20--200Hz. Walk the room. Where it gets louder = standing wave node.
Monitor phase check: Play 100Hz mono. Flip polarity on one speaker. Volume should drop dramatically if they're in phase.
Speaker test: Pink noise at moderate volume. Listen for buzzes, rattles, or uneven frequency response.
Hearing check: Sweep 20Hz--20kHz. Note the frequency where the tone drops out -- that's your hearing ceiling.
Ear training: Pick a note. Identify it. Use the note pills to check common musical reference tones.