4 - Header (MUSX)
4 - Unknown
4 - Unknown (6)
4 - Unknown
8 - Hash?
4 - Unknown (1)
4 - null
4 - Directory 1 Offset (2048)
4 - Directory 1 Length
4 - Directory 2 Offset
4 - Directory 2 Length
8 - null
4 - First File Offset
4 - Unknown
4 - Unknown

X - Padding to offset 2048 (using byte 171)

// DIRECTORY 1
  4 - Number Of Files

  // for each file
    4 - File ID?
    4 - Offset to File Details [+dirOffset]

  // for each file
    4 - Unknown ID Number
    2 - null
    1 - Unknown
    4 - Unknown
    4 - Unknown
    4 - File Size?
    4 - File Size?
    1 - null
    4 - File Size?
    4 - null
    4 - Unknown (0/1)
    14 - null
    2 - Unknown (0/10)
    2 - Number Of Groups

    // for each group
      2 - Unknown
      2 - Unknown
      4 - Unknown (100)

X - Padding to Directory 2 Offset (using byte 171)

// DIRECTORY 2
  4 - Number Of Files

  // for each file
    4 - Unknown (0/1)
    4 - File Offset (relative to the first file offset)
    4 - File Length
    4 - Sound Sample Rate? (22050/32000)
    4 - File Length
    4 - File ID? (starts at 0, increments by 96)
    4 - Unknown (0/1536)
    4 - Unknown ID Number

X - Padding to First File Offset (using byte 171)

X - File Data