Try this - Reset the iPad by holding down on the Sleep and Home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons. (This is equivalent to rebooting your computer.) http://support.apple.com/kb/ht1430
iPhone: No sound or distorted sound from speaker
To solve some sound problems, just follow these simple steps
1. Go to Settings
2. Tap on General
3. Tap on Reset
4. Tap on Reset All Settings
What this effectively does is to reset some of your Settings to factory default. It’s not a complete removal of settings. It removes all of your preferences for Wi-Fi, Bluetooth, Do No Disturb, Notifications, General, Sounds, Brightness & Wallpaper and Privacy. It doesn’t affect your data. All of your email accounts will remain intact, as well as any SMS text or iMessages.
Thanks for your reply. I've already tried a hard reset though along with restoring factory settings and a full system restore via iTunes. I've also replaced the headphone jack flex cable and looked up a few other theories on what this could be. Some of the other things I've forgotten but one that I tried (that seemed to work for a lot of people) was in accessibility settings: turning mono sound on and off again (as well as every combination of turning it off/on restarting the ipad in between etc). That didn't work for me though.
It's a complete nightmare! :( cheers anyway though!