To play back audio from an SD card which was not originally recorded with your CQ, the folder structure and file naming/format of a CQ recording must be mimicked exactly.

This can be achieved using a combination of audio editing applications and the simple renaming and organisation of files using Windows Explorer or Finder in macOS, with attention to the following important points:

• Audio files must be mono *.wav files with no meta data included.
• All files must be either 48kHz or 96kHz.
• All files must all be exactly the same length/size.
• Each file must be named 'xxyyyyyy.WAV' where xx is the USB channel number the audio will play back to, and yyyyyy is the channel name (note that the channel name is only taken when recording and has no relevance to playback).
• Each multitrack folder containing all audio files must be placed inside a '[SD]\AHCQ\USBMTK\' folder, on a SDHC card which has been formatted in the CQ.
• Recordings made by the CQ will have multitrack folder names 'CQ-MT001' 'CQ-MT002' etc... but these can be renamed.

The easiest way to ensure folder structure and naming convention is matched is by using the CQ to make a quick multitrack recording to SD. The SD card can then be connected to a computer and the folders can be examined.

It's also possible to carry out the whole re-rendering/re-naming process using Reaper (https://www.reaper.fm/) as follows:

Prepare the SD card:

• Format the card using the CQ in the 'HOME / SYSTEM / USB/SD (Symbols)' screen.
• Remove once complete and connect to computer.

Get audio into Reaper:

• Load all audio file(s) into reaper by dragging and dropping the file(s) into the timeline view.
• If importing multiple files at once, select the 'Separate Tracks' option.
• Split any stereo tracks out to two mono tracks.
• If required, move files around so they are on the track numbered the same as the USB channel you want them to play back from on the CQ later.
• If wanting to play back any stereo pairs of tracks to a stereo channel on the SQ later, ensure these are on an odd (left) and even (right) pair of number. e.g. Left on track 3 and Right on track 4, or Left on track 9 and Right on track 10.
• Rename the tracks to help identify them later, using names no longer than 6 characters.
• Playback in Reaper to check all audio is aligned and as expected before continuing.

Select the audio to use:

• Select all tracks you wish to render on the left.
• Highlight a time selection using the top bar. This will ensure all files are the same length when rendering.

Render new audio files:

• Go to 'File > Render'…
• Use the following settings (anything not described in the text below is up to you and relates mostly to quality/speed of render):
  
   
  
  • Source: Selected tracks (stems)
    
  • Bounds: Time selection
  • Directory: '[SD]:\AHCQ\USBMTK\CQ-MT***' where the multitrack folder name ('CQ-MT***') can be any multitrack folder name/number that has not previously been used.
    Note that rendering directly to the SD drive may be slow, in which case, simply render to a local drive (such as your main hard drive) first, then copy files across to this folder on the SD card when rendering has completed.
  • File name: '$tracknumber$track' - this is the track number wildcard which will tell the CQ which channel to playback the audio to, followed by the track name wildcard. The total length of the file name must not exceed 8 characters in total (2 characters for the track number and up to 6 characters for the track name).
    
  • Sample rate: either 48000 or 96000
  • Channels: Mono
  • Ensure 'Tracks with only mono media...', 'Multichannel tracks...', 'Metadata' and other boxes are not ticked
  • Format: WAV
  • WAV bit depth: 24 bit PCM
  • Large files: Force WAV
  • Ensure 'Write BWF ('bext') chunk' is not ticked
  • Select 'Do not include markers or regions' in the drop down below the BWF option
  • Ensure 'Embed tempo' and all 4 other tick boxes below are not ticked
• Click 'Render * files' where * should match the number of files you are expecting to render.

Done! You should now have correctly formatted audio files on your SD card in the correct location and can therefore playback using your CQ as if it were a multitrack recording made by the mixer itself.