Many planar magnetic headphones have a sensitivity far below 100 dB and require very powerful amplifiers to drive. The OPPO PM-3 has a sensitivity of 102 dB, which allows it to be easily driven with mobile devices. Its low impedance works well with smartphones that ship with low impedance ...
The PM3 was regarded as the best closed back headphone (it as the best closed back planer magnetic). And HA-2 is regarded as one of the best amplifiers. Sennheiser is also a great brand and Sennheiser has a far greater legacy in headphones but that doesn't mean Oppo is any less. ...