B9Scrambler
Headphoneus Supremus
My thoughts on the BS1 Official. For 99 bucks, they're kind of a no-brainer.
https://www.head-fi.org/showcase/penon-bs1-official-version.22858/reviews#review-19964
https://www.head-fi.org/showcase/penon-bs1-official-version.22858/reviews#review-19964