We've put together a comparison of these two impressive headphones GRADO RS2e vs Beyerdynamic Custom One Pro Plus. Both headphones have the same overall rating of 7.5.
Advantages GRADO RS2e over Beyerdynamic Custom One Pro Plus
Higher sensitivity: 100dB vs 96dB
Advantages Beyerdynamic Custom One Pro Plus over GRADO RS2e
Better low limit of frequency response: 5Hz vs 14Hz
Better high limit of frequency response: 35KHz vs 28KHz