At this point, I bet you’re wondering how these headphones sound. Well, as I excitedly hit the Play button on the first track, I had high hopes and was ready to be blown away. Yet I wasn’t immediately blown away, and interestingly, that’s part of the magic of the 660S phones. You see, the music that pours through them is beautifully flat and clear. On initial first use, when I first hit that Play button, I was expecting the sounds to truly stick out. Instead, what I heard was an even, natural sound, sort of an anomaly in music these days. So once I relaxed and really listened to the track, I discovered how the vocals took over the soundscape without being belligerent; how every instrument had its own space in the mix, which allowed them to breathe dynamically; how the effects on the vocals had more depth and clarity than I’ve ever noticed before; and how tracks that I’ve listened to for years suddenly felt remastered and fresh.
Yes … now I was blown away.
What you’re getting with these headphones are all of the hidden details in the tone and timber of the music that have been hiding just under the surface of your favorite songs. They’re so subtle, in fact, that it took me a few minutes to fully appreciate them and what a pair of “reference” headphones are supposed to do.
I found that the 660S phones stood out most when listening to a musically busy track with a lot going on. Songs that have many layers of instruments and effects can sometimes sound mushy and undefined, especially during high-energy parts. But the 660S phones don’t flinch during these portions of the musical composition; rather; they offer the same clean, open sound one might hear on a soft, uncomplicated song.
The only area in the sound spectrum of these headphones that I found to be somewhat underwhelming was the low end, which I would describe as “undramatic.” Sure, there was still some punch as well as strong definition here—a definition, I might add, that is often lost on most headphones and speakers—but it felt like the low-end sound was lacking power within the sub bass. Nonetheless, this flat low-end sound gels well with the rest of the sounds heard on the headphones, and I appreciate the consistency of that naturalness, which, as mentioned, the 600-series phones are known for.
One reason I choose the 660S over their older siblings (the 600 and 650) is because of their nominal impedance of 150 ohms. This allowed me to plug them directly into my laptop without a headphone amp. While I can do this and the level is comfortable, I’m excited to explore what they’ll sound like with a proper headphone amp. I listened to a few of my favorite vinyl albums while plugged directly into my stereo headphone output and noticed a dynamic improvement.