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.
Sub bass test: 30-50Hz sine at moderate volume. If your system can't reproduce it, it won't handle 5-string bass or dropped tunings. Try B0 (31Hz) and E1 (41Hz).
Channel isolation: Use L/R buttons to verify stereo routing. Crossed cables or bad patches will sound on the wrong side. Confirm mono sum with "Both" and then flip one speaker polarity.
Room decay: Hit Impulse. Listen for the reverb tail. Longer decay = more reflections. Count milliseconds until silence to estimate RT60.
Binaural beats / IMD: Set a tone and add a small dual-tone offset (e.g., 10Hz). Two tones 10Hz apart create a 10Hz pulse sensation. Larger offsets reveal intermodulation distortion from speakers or amps.