The Sennheiser HD 660S are good headphones for critical listening. They stand out because they are a good deal for what you get. They are pretty comfortable, but they are a bit tighter than some other models on the market, and they don’t sound as open as other critical listening headphones we’ve tested so far. The headband of these over-ear headphones has a lot of padding, and the padding around the 70mm x 40mm ear cups is very soft. This is typical of Sennheiser’s headphones in this price range.
The 260g weight feels pretty light on my head. I can wear it for a long time without getting too hot, which is great. You can remember your size setting by looking at the notches on the headband and counting how many clicks each adjustment of the metal mechanism makes. Overall, the fit and finish of this black-on-black headset are top-notch, and the silver Sennheiser logo is subtle and tasteful. One small thing that bothers me a little is that both the left and right ear cup connectors are made of black plastic.
In earlier versions of the HD series, there was a red connector on the right side, which made it easy to find the right channel. Portable headphones are usually at the top of most people’s lists of things to buy these days. But the Sennheiser HD 660 S show that full-size open headphones like these are usually better if you just want a pair to use at home. Their soundstage is very good. It has great stereo imaging and spatial imaging, so your ears can explore arrangements much better than with almost any closed pair at this price.
You also want a big sound for movies, so that it feels more like you are surrounded by speakers and less like the sound is “in your head.” The 660S are open-back headphones, which makes the soundstage better but also lets a lot of sound out. They don’t block out any sound at all, and even with the volume turned down, I could still hear the fans on my computer.
It could be distracting to people in the same room, but when you move a couple of metres away from the headphones and turn the volume down to a comfortable level, you can barely hear the sound leaking out. The Sennheiser HD 660 S are in a strange place. The way they look and fit is a little different from the pretty standard-looking HD 660 S. The Sennheiser HD 660 S headphones are comfortable and have a great soundstage. They also have a mix of clarity and rich tone that doesn’t get old.
