The Koss Porta Pro came right in the middle of the 80s, not long after the popularity of portable cassette players and the rise of portable listening use.It’s a very small and nomad…

○ Release : 2004○ Current status : In production○ Type : On-ear / Open-back○ Measured weight : 45g○ Impedance : 60 Ohms ○ Sensitivity : ~99-101 dB/mW○ Average used price : $10-15 Sound…

The ESP950 is an electrostatic headphone and has been manufactured by Koss since … 1990. That makes it one of the oldest headphones still in production to this date. Retail price is $999…