Hi mistapuggs,
When using makehex you have to make sure you are using the correct Protocol for the IR Hex codes you are generating.
Marantz use rc5 and rc5x Protocol.

rc5 uses two digits eg. 11 16 (VOLUME +).
11 is the device number and 16 is the function number.

rc5x uses three digits eg. 11 12 01 (POWER ON).11 is the Device number,12 is the Sub Device number and 01 is the function number.

When you use makehex edit the IRP File for rc5,
eg. 11 16 (VOLUME +).
Device=11
Function=16
Or you can generate all 128 codes for that device (Function=0..127)

For rc5x,
eg. 11 12 01 (POWER ON).
Device=11.12
Function=1
Or you can generate all 64 codes for that device (Function=0..63)

VOLUME +
Device Code: 11 Function: 16
0000 0073 0000 000A 0020 0020 0040 0020 0020 0040 0040 0040 0020 0020 0040 0040 0040 0020 0020 0020 0020 0020 0020 0CC5