Last covered here in my round-up of audio capture utilities (which it won), Audio Recorder Pro has been steadily updated, with the latest update rounding out OneDrive support, for uploading your recordings. See below for the full changelog - highly recommended.
Here are the changes since for v18.104.22.168 since the version covered in the round-up:
Re-added OneDrive support on Windows Phone 8.1
Changed file extension from 'mp4' to 'm4a'
Fixed playback problem after recording WAV files
Added option to select recording device (WP 8.1 only)
Fixed stereo recording
Fixed bug to recover old WP8 recordings on WP 8.1
Added 8.1 support: audio files are now stored in Music/Audio Recorder Pro folder
Added option to share audio files with other apps
Quite an update then, for a top utility. Here it is in action on the Lumia 1020 running Windows Phone 8.1:
Recording in action in the full version of the application (there's a trial version with ads), note the VU meter across the top of the screen;(right) uploading a recording to OneDrive
Experimenting with some of the recording device and audio format settings - plenty here to try out!!!
Arguably, there's too much to fiddle with here - but then if you're after ultimate quality...?