QZ77 full review
These in-ear headphones penetrate deep into your ear canal, so they’re an effective seal against exterior noise even when turned off. Switch them on and enjoy a rich, well-balanced sound, boosted by electronic noise-cancelling technology. The headphones use a single AAA battery, but even without batteries they still deliver some sound.
In-ear headphones aren’t for everyone. The soft tips on these might be too large for some people, even when rolled up tightly before insertion. Of four testers on the listening panel, two had difficulty securing these in their ears. There were also complaints that the QZ77’s are prone to falling out as they expand. Koss should ideally offer different-sized tips for different ears.