Q: sound problem when I use external devices

Poor quality through the headphone jack can be caused can be caused by dirty/damaged jack.

Try cleaning the headphone jack.

For the other outputs:

- Reset the iOS device. Nothing will be lost

Reset iOS device: Hold down the On/Off button and the Home button at the same time for at

least ten seconds, until the Apple logo appears.

- Reset the BT headphones/BT device

- Reset network settings: Settings>General>Reset>Reset Network Settings. You will have to rejoin wifi networks and re-pair BT device

- Restore from backup. See:

iOS: How to back up

- Restore to factory settings/new iOS device.

If still problem and it does not connect to any networks make an appointment at the Genius Bar of an Apple store since it appears you have a hardware problem.

Apple Retail Store - Genius Bar

Do you have the equaliser setting turned on on the iPod?

Glad to hear that.

Possibly, what has happened is that an already heavy bass track (for example) simply overloads the headphones if the EQ is too high.