When Sennheiser announced that it would be licensing the development of its consumer products to Sonova AG, a hearing aid giant based in Switzerland, I was skeptical. At the time of the announcement, I interviewed, joint CEOs of the venerable German headphone company. What they told me at the time, largely allayed my fears. However, I knew the new products developed by Sonova AG would be the acid test of the cooperation.
The new HD 620S have a high damping factor and use a 150Ω aluminum voice coil which means the headphones do need a high-quality source like a headphone DAC or a Digital Audio player. The result is an exciting and punchy sound with plenty of dynamics across the entire frequency spectrum which stretches from a gut-rumbling 6Hz to a bat-squeaking 30kHz. They have the sure-footedness and agility of an open-back pair of headphones but with all the advantages of a closed-back design.
The 1.8mm cable is terminated with a 3.5mm stereo jack plug. There’s also a screw-in 6.3mm adapter for listening with hi-fi systems. The cable is detachable and has a 2.5mm jack plug with a clever locking mechanism that keeps it attached to the left earcup. Later this year, Sennheiser says it will be launching a balanced cable with a 4.4mm Pentaconn connector and I’d love to try that with a digital audio player like the excellent FiiO M23.So far, so good.