Prices valid in stores (all including VAT) until close of business on 29th November 2023. (Some of these web prices are cheaper than in-store, so please mention that you've seen these offers online.) It’s easy to confuse clear and well defined highs with sibilant highs – one of the biggest mistakes that I see coming from some online publications. Some consider the HD 660 S to be sibilant but I tend to differ completely, I consider it having clean highs, without highlighted extremities. Sennheiser HD660S + Burson Play - Burson Play is a great little device created by Burson, a rather loved and well-known company. Play is most an Audiophile-Grade, modular, integrable DAC/AMP for desktop, and especially for desktop PCs. Its power is quite fit for HD660S, and it is a good way to prove that HD660S can sound pretty sweet on a proper desktop-class setup. The beauty of Burson Play comes from the fact that you can integrate it in your PC setup, so you can plug HD660S, or any other audiophile-grade headphone, directly in your battle station, and just enjoy audiophile-grade sound without having more devices on your desk or table. The sonic performance is quite variable with Burson Play, as it allows the user to change its OP-AMPs, but the most basic configuration offers a warm and smooth sound, with a pretty good soundstage, which pairs well with HD660S. On this note, they are more open than either Audeze LCD-MX4 or Beyerdynamic Amiron which we reviewed before, HD660S leak quite a bit more sound and they isolate less than either of those two models.

This problem is no longer present on the HD 660S and this is probably one of the best improvements of the new model. I'm a 26 year old firefighter, for the City of Concord, North Carolina as well as the U.S. Army, North Carolina National Guard. The cliché of wanting to do this since I was born couldn't be more present with me. I've worked hard over the last several years to earn this position and now it's time for me to work even harder to keep it. The HD 660 S has been created to enjoy music in supreme quality and from many different audio sources. Thanks to its low impedance it also offers reference-class fidelity with hi-res mobile players. Naturally, the HD 660 S reveals its full potential when it is connected to the balanced outputs of a dedicated headphone amplifier such as the HDV 820 or to the balanced output of a mobile digital audio player. Accordingly, it comes with a choice of cables for just about any occasion. All cables are made of highly conductive OFC copper, featuring very low handling noise and sturdy para-aramid reinforcement. Like the build quality, comfort is also very good on the HD 660S. Thanks to their mostly-plastic construction, these are extremely light (only 260g or so), so I doubt anyone will have weight issues with these. The pads use a fairly dense foam wrapped in velour and are very soft on the skin, I only wish that they were a bit wider on the inside as some people’s ears might touch the inner sides of the pads. The only problem I have with the comfort is that out-of-the-box, the clamp force can be quite vicious. Nonetheless, this can easily be alleviated by extending the headband all the way out and gently flexing the part that extends.

During my time with them, post the slight bending, I had no issues with having them on my head and listening to them for several hours without any fatigue. They stayed firm in place regardless of my lying position and truthfully, I really enjoyed how they felt on my head (again post bending [which again I stress to do at your own risk]). Perhaps time will break these into the forming sand the HD650 is to me but even if it doesn’t, what’s so wrong with the loving brace of a relative who really misses you?

In conclusion, I don’t recommend you to plug them directly into a smartphone, but if you add a portable amplifier to the mix, things will get radically better.

How does the Sennheiser HD 660S sound?

Everything else is left at default, the master is usually brought at least at -7dB to avoid clipping. The driver has multiple layers of protection, but none of them seals the driver, as Sennheiser HD660S is an open headphone to the largest extent of it. The highs on the HD 660S are definitely the brightest of the HD 600-series headphones, and while I would not call them veiled, they are definitely still on the warmer side. For frequency response I only had two minor issues with the HD 660S’s treble. The more noticeable one was a peak in the lower treble at 5.5k, that–like on the HD 58X–made the HD 660S’ timbre sound a little bit more congested than on the HD 6XX and HD 600. Additionally, the frequencies above 10k could use a little more energy for my preference, I thought that they sounded a little muted. Aside from that, I still really enjoyed the treble and I found it to be very smooth overall. For resolution I think that they have very good detail in the highs; they are very resolving and clean in their delivery. Comparing them to other Sennheiser headphones, I thought that for resolution they were a little more resolving than the HD 6XX, and were a significant upgrade in treble detail from the HD 58X. I personally thought they were more detailed in the highs than the DT 1990 Pro, and they were on par with the HiFiMan Sundara. Soundstage and Imaging The padding in the new HD660 S feel very firm to the touch and offer a really nice level of both give and support. This may be because these are a brand new pair and my HD650 is, how should I say, well experienced, the padding looks to be a little bit deeper than my ol faithful HD650. This is a good thing because my ears no longer touch and rub against the cloth covering the drivers.