If you want just a high quality audio recorder to use with a separate microphone the Zoom F6, or F8n would be a good choice. No need to set levels because they

If you want just a high quality audio recorder to use with a separate microphone the Zoom F6, or F8n would be a good choice. No need to set levels because they capture the entire dynamic range, and dual SD cards. Kind of big though. Sound Devices makes similar boxes, of similar or better quality but much higher price.