SENNHEISER HD 660 S - HiRes Audiophile Open Back Headphone

The headphones have natural and pure sound, typical signature of Sennheiseir with strong bass, detailed mids and sweet highs. This should be used with a headphone amp. However At $500 there are several options to compare, these are Like New at $350, so, ...

They’re worth it.

Just received and left speaker blown out of box.

The way these things get reviewed and talked about, youd think they were actually worth the large entry fee. I found them to have virtually zero high end. I realize they are not meant to have sparkly highs, but holy crap - it sounds like youre wearing them over a ski mask. Build quality is good, comfort is good, weight is good - I just couldnt EQ them enough to sound reasonable. Returned them immediately. And dont start with the they werent broken in crap. There was no recovering from that. So, bottom line, try before you buy.

The amount of detail in these are very impressive. A punchy but balanced sound signature will keep you engaged in all kinds of music. Open-back design creates very immersive sound staging, but sound VERY easily bleeds through as a cost. For gaming, these are great headphones, just keep in mind that your mic may pick up noise if you play on high volumes. For music, I have no complaints. No discernible distortion at various volume levels after first few days of listening, and these arent even broken in yet. I highly recommend if you have not owned high-end headphones yet, and if you enjoy hi-fi audio. I also recommend a quality amp to unlock the full potential of these headphones.

Good but 6xx still better overall value

These were tested against the Hifiman Sundara. The Sennheiser has a clearer mids/vocals; however the overall sound, especially the lower end, favored the Sundara. The Sundara was priced at $350 vs $400 for the 660S. DAC AMP used were the S.M.S.L. M500 and Fiio M11 Pro. I ended up going with the Sundara.

Im coming from a set of Beyerdynamic dt990pros, which are apparently notorious for being too harsh in the high-end so I was a bit disappointed in the lack of high end clarity... At first. Since using them as my primary set for a while, Im understanding why folks think that, and they sound more natural than they did at first, though the dt990s still feel like home to me.

This is better then I thought it was going to be! You don’t even need a microphone.

I really was excited to get these headphones and wanted to love them but they have a muffled flat sound. My Grado SR60s have a fuller sound and cost about a fourth of what these cost. I am most likely going to send these back.