“I am happy about the sound profil and the quality. The retail price is kind of ridiculous though”

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“I am happy about the sound profil and the quality. The retail price is kind of ridiculous though”
“They are my go-to primary headphones.”
“I wouldn't say the 660S2 is an upgrade. It's really on a similar technical level to the 600, but the tuning is quite different. I didn't like it as much as the 6XX and 600.”
“I bought the 660s2 open box for only £269, and just a bit better over my moded 6xx , but quite close .”
“It's not just louder bass. It's more nimble, more detailed. Play a song with a fast, complex bass line, and you'll hear each note individually on the S2, while the 6XX blurs them with or without EQ.”
“I had the hd660s2 i was very disappointed with them... boring tone. Everything sounds the same, IMO.”
“I just listened to it today and was severely disappointed, especially taking its price into consideration. Its bass sounds bloomy and although the treble isn't very fleshed out, mids still manage to sound recessed somehow”
“I absolutely love the HD660S2, definitely an upgrade to the HD600”
“It does, however, create a fatigue free and pleasant listen to me. After a while I was totally comfortable with the sound. Won't beat my HD800 (EQ'ed) though and is not as well extended in the bass and does not have the clarity of the S5X”
“I wouldn't say the S2 is disappointing but you wont be immediately impressed as it's very neutral however it grows with longer listening sessions and at least myself do not get fatigue from them. I am a musician and I would say they sound a lot like music”
“the S2 is my favorite of the 600 series. By a wide margin. I enjoy the added kick in the pants out of the bass performance as well as the extended upper frequencies.”
“Just received my 660S2'S today wow what a difference from the 6XX”
“660s2 is bright and aggressive but distinguishing frequency separation could be better”
“In a way it reminds me a lot of my beloved 650 but better ,enough so that I am finally selling 650 and bying 660s2.”
“660 S2 are great headphones!”
“Tested a heap of headphones under $1000. To my ears these were clearly the best. (Including the 650 etc.,)”
“just got the 660s2 for $400 and I paired it with mojo2 sounds amazing”
“These at the more recent 400 dollar price point are excellent, I use 600s as my studio headphones and the 660s2 has replaced my 6xx as my home listening headphones.”
“I found the 660S2 to have more punch, making the orchestra more power. The bass had more ooomph to it, and yet sounded very natural.”
“I really recomend it they blow up my mind when I listent to with my cheap tube amp.”
“To me the 660s2 seems more detailed and extended, as well as being clearer.”
“The best thing in my opinion ist the very very precise and clear bass of the 660 S2.”
“my first sennheiser headphones and I have to say they are here to stay.”
“I have both and like them a lot. HD660 S2 are easy to power than HD650 and less amp picky.”