Headphones are a necessary part of every musician's toolbox. They used to be considered just an accessory.  With them you can track and practice sessions or monitor live – even to mixing – you need at least one great-sounding pair of headphones.

 In-ear phones wouldn't be the first choice for mixing or any sort of reference-quality listening.
Long session can get uncomfortable, which is why supra-aural phones with ear pads have become common.

While I didn't notice if anyone in the band at the last sermon I saw had headphones, the sound was supreme.

But if I needed headphones, those are the type I would invest in.  I wish I could sing like I did when I was young.