Rating: 
Summary: Good sound and value
Review: First let me say that they are a good value at the current price of about $40. I'm not sure they are worth too much more. That said, I am very happy with the sound quality of these headphones. The one surprise I had was that I could hear artifacts in my MP3s while using these. The artifacts were especially noticeable if I enabled their "surround sound" feature. However, if you disable the surround sound or re-encode your MP3s at a very high bit rate (256 kbps) you should be fine. Not surprisingly, there are no sound quality issues while listening to CDs.The closed ear design and non-breathable padding make your ears sweat a bit, but it isn't too much of a hassle. Finally (others have mentioned this too), the documentation is terrible. The only information you get is printed on the back of a card included in the package. It tells you how to enable the surround sound feature, but that is it. Even with these downsides I still think these are a great value for $40.
Rating:
Summary: Good sound and value
Review: First let me say that they are a good value at the current price of about $40. I'm not sure they are worth too much more. That said, I am very happy with the sound quality of these headphones. The one surprise I had was that I could hear artifacts in my MP3s while using these. The artifacts were especially noticeable if I enabled their "surround sound" feature. However, if you disable the surround sound or re-encode your MP3s at a very high bit rate (256 kbps) you should be fine. Not surprisingly, there are no sound quality issues while listening to CDs. The closed ear design and non-breathable padding make your ears sweat a bit, but it isn't too much of a hassle. Finally (others have mentioned this too), the documentation is terrible. The only information you get is printed on the back of a card included in the package. It tells you how to enable the surround sound feature, but that is it. Even with these downsides I still think these are a great value for $40.
Rating: 
Summary: Nice sound, but fragile
Review: I bought a pair of these a few months ago, and was quite happy with the quality of sound and the comfort of the headphones. However, after about three months of use, one of the plastic pieces that connects the ear cup to the headband snapped. Looking at the other side revealed that it was developing a crack in the same place. I could probably get the headphones fixed under warranty, but the cost of shipping to do so would be about half of the value of the headphones themselves. Since it's obviously a design problem -- far too much stress is placed on those flimsy plastic pieces -- I hate to send it back when it seems likely that they'll just break again in another three months. I'll probably find some other set that isn't as likely to fall apart. It's certainly a shame, because reinforcing that piece probably would only cost them an extra few cents, and would make the product much more durable.
Rating:
Summary: Background Noise
Review: I chose the R100s primarily to use while mowing my lawn on a LOUD and NOISY ride on garden tractor. The R100s sound great, shield the external noise very well, and are very comfortable to wear. I will be using them for much more than just mowing the lawn! The headphones come with two 8 foot coiled cords that plug into the bottom of the left earcup with a jack similar to those found on telephones. Both cords have 1/8" ("Walkman") jacks, but, the R100s also include a 1/4" adapter for a home stereo. One of the cords has inline 3D mixing device, which Koss calls a Phase II control. I found the cord with the Phase II control reduces the volume of the audio substantially. The documentation provided states that a decrease in the sensitivity when using the Phase II cord is a "normal occurrence." When the normal cord is used the sound is clear and exceptional and the bass response is outstanding. The headphones are lightweight and are comfortable to wear for extended periods thanks to the extra padding on the headband and multi pivoting earcups. I found I have been able to wear them for 4-6 hours without any discomfort.
Rating:
Summary: Great sound without Phase II Cord
Review: I chose the R100s primarily to use while mowing my lawn on a LOUD and NOISY ride on garden tractor. The R100s sound great, shield the external noise very well, and are very comfortable to wear. I will be using them for much more than just mowing the lawn! The headphones come with two 8 foot coiled cords that plug into the bottom of the left earcup with a jack similar to those found on telephones. Both cords have 1/8" ("Walkman") jacks, but, the R100s also include a 1/4" adapter for a home stereo. One of the cords has inline 3D mixing device, which Koss calls a Phase II control. I found the cord with the Phase II control reduces the volume of the audio substantially. The documentation provided states that a decrease in the sensitivity when using the Phase II cord is a "normal occurrence." When the normal cord is used the sound is clear and exceptional and the bass response is outstanding. The headphones are lightweight and are comfortable to wear for extended periods thanks to the extra padding on the headband and multi pivoting earcups. I found I have been able to wear them for 4-6 hours without any discomfort.
Rating: 
Summary: Poorly Made
Review: I had Koss R10, they were pretty good but plasic parts are got broken fast. Since Koss have lifetime warranty I send them back. Now I bought R100's and they are awsome! Sound is great. Bass is deep and clear. Good buy.
Rating:
Summary: Great for the price!
Review: I had Koss R10, they were pretty good but plasic parts are got broken fast. Since Koss have lifetime warranty I send them back. Now I bought R100's and they are awsome! Sound is great. Bass is deep and clear. Good buy.
Rating:
Summary: Poorly Made
Review: I have always held a high degree for KOSS equipment, but the earphones that I received (advertised as PRO) are horrible. For one the sound is extremely muddy and almost void of any decent high frequency. Two it seems in this day and age of The Internet and Space Shuttles that man still can't make a pair of headphones that don't short out at the plug! I do have to admit that I gave these headphones a 1 star review, for comfort and they are pretty. ;-P
Rating:
Summary: Background Noise
Review: I purchased the headphones so I could listen to my radio as I cut the grass. They work very well for this purpose. It is hard for you to judge the noise reduction from an evaluation but here are some benchmarks. When I use my 3-½ hp gas walk behind mower I could not listen to my radio with the headphones that came with the radio. I had to have the volume on max and not only was it uncomfortable to listen to I thought it would be dangerous to my hearing. When I use my electric walk behind mower (75db, the blade makes a lot of noise) I had the radio about 25% to 33% louder than if the mower was not running. I could listen to the radio but it was a little too loud. With the new headphones and the electric mower I have the volume at normal or sometimes about 10% higher than normal. I hear the radio clearly and the noise from the lawnmower is about 50% of what it was without the headphones. The radio sound seems to come from the center of the headphones and the outside noise is in the background. I think the quality of the reproduction of sound helps cut down on the background noise. If you put the headphones on with no radio you can hear the TV or talking in the room without much trouble. However with the radio on the background sounds fade away. I use the mix cord that comes with the headphones on a radio that is not stereo. Instead of having sound in only one ear the mix control lets me have sound in both ears.
Rating:
Summary: Portable Sound Par Excellence
Review: I tried out several headphones including open air and other earcupped designs. I found the best results with this set. Also with the price that [they are offered] for, I found that this was also the best deal for the sound quality that I was in search of. The two seperate 8 foot cords are both useful. The Phase II cord gave me the best results for use on a home system which provided the extra umph to make the headset sound incredible. The ability to customize the 3D surround sound is a great option and sounds very nice when used on a decent home stereo system. Using the Phase II cord didn't yield the same results on any of the portable CD players that I used. The volume was noticeably lower and the bass quality was substantially decreased as well. Better results were produced using the regular cable for use on portable devices and low-end stereo systems. I received higher sound volumes and better bass response using the regular cable. Lightweight, comfortable, high-quality sound, and low price ..., you can't find a better set of headphones than these.
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