Found these by accident and didn’t see them documented anywhere online. These actually became very useful to me for reasons I’ll explain in a future blog post :)

These exist in firmware version 1.18A, not sure about others. Hold while powering on.

• COMPARE + SETUP + SUM - Production Test, system functions
• MUTE + STORE + RECALL - Production Test, audio functions

This is in addition to the following, which are documented. Again, hold while powering on.

• IN A - Receive firmware update over RS-232
• PAGE LEFT + PAGE RIGHT - Factory reset

COMPARE + SETUP + SUM will take you through the following steps, pressing OK to continue to the next:

1. LCD Test - Displays some test patterns, rotate knob to set contrast
2. LED Test - All LEDs on
3. LED Test - LED matrix column test
4. LED Test - LED matrix row test
5. Button Test - Press all buttons, then you can press OK
6. Encoder Test - Rotate knob to +/- 20 steps, then you can press OK
7. RS232 Test - Not sure what data this sends or expects to receive. Maybe wants a loopback?
8. RS485 Test - Sends alternating high, low, and off levels on RS-485
9. Testing Flash - Erases and reads and writes some blocks. Might wipe your settings!
10. Testing 96kHz - Always just says “SAMPLE RATE: OK”. Not sure what exactly it is testing.

And the following for MUTE + STORE + RECALL:

1. Analog Out Test: All Digital Zero
2. Analog Out Test: All 1kHz -2dBFS - Note this one is probably going to be pretty exciting if you have speakers connected.
3. Analog Out Test: All 1kHz -2dBFS, Active Analog Mute
4. Analog In Test: IN A to OUT 1 + 4
5. Analog In Test: IN B to OUT 2 + 5
6. Analog In Test: IN C to OUT 3 + 6
7. Analog In Test: IN C to OUT 3 + 6, Second Gain Stage
8. Digital In Test: IN A to OUT 1 + 2