Cologne (dpa) — On-ear, in-ear, over-ear. Wireless or wired. With a headband or without. Headphones come in every conceivable variety. Which ones are right for you depends primarily on how you plan to use them. True wireless earbuds are currently particularly popular. “This means completely wireless headphones in the form of two in-ear earpieces that can also be conveniently carried in a trouser pocket when not in use,” says audiophile and audio tester Christoph de Leuw. Suitable for sports? Wireless in-ear models can work for sporting and fitness activities such as running, but there are limi…