Denon AHC751K In-ear Headphones (Black)

Comment: To begin with full perspective, I am a Denon fan. My home theater and stereo equipment is nearly all Denon, aside from my speakers, which are JBL, Harman Kardon and Sony. I love my iPhone and carry a great deal of music in it, recorded/transferred at the second highest bit-rate to balance high-end sound with fitting the greatest volume of music on it possible. Music is extremely important to me and I care a great deal about sound quality.

The sound of these Denons is very good and, as others have said, there is a "burn-in period" that takes place before the best sound quality is reached with these. They do get warmer and better.

First, what I DON'T LIKE is that:

1. Denon has bizarrely boasted about including an extension cable that "extends the listening range" of these. That's so ridiculous, though, considering that the primary cable is about 1.5' long. Who can use that?! Let me answer that... NO ONE CAN. So you will need to use this silly extension cable if you don't want to attach your iPod (or whatever you use) to your shirt collar. That would certainly be strange. To me, any time you introduce a break in a cable wherein you must also use a plug-in/connector, you compromise the sound quality and/or continuity, no matter how minimally. So this is the largest flaw to these. I sure wish I could make sense of why Denon did this. Maybe they sourced scrap cable for less money and had to make the remnant pieces work???
2. Denon spent very little to design and construct the "hard shell carrying case" that is also included. With the cable connector that I mentioned above, it's almost impossible to coil and fit your cable into this case connected/intact. And so again, to me, the more frequently you connect and disconnect the coupling you where out that tight fit and super strong connection. So I ended up buying a padded digital camera case for these and I don't bother to use the case Denon has included.

And what I DO LIKE is:

1. Again, the sound is very good for in-ear phones and gets better with early use, again known as the "burn-in period".
2. The "can" of these in-ear phones is heavy gauge aluminum and very durable.
3. They are elegant in their appearance.
4. They're Denon.

It pains me to not give a perfect five stars on these for Denon, but I would want others to make me aware of these details. Like many of us, I, too, read countless reviews for weeks before buying. I do get a lot of use out of these and if you take my comments into consideration I believe you will be happy with these.

All the best to you in your own decision making!

Comment: These are excellent for casual listening, I have no complaints in that regard and only good things to say. However, I was looking for a pair of earbuds that I could wear while I work out when I got these, so that's what I'm reviewing them for. By working out I mean lifting weights, olympic lifting and split training, not running or swimming. If you don't care about that, you can skip to the part about the sound quality.
I wanted a pair that had a sound quality at least one step up from the ipod earphones and that wouldn't bug me or fall out every time I moved my head, and that I wouldn't be overly aware of.
I read some reviews commending the lower end Denons as good workout buds, but I had also read that anything the cord touches would translate to noise in your head, regardless of how high the volume was turned. I got a really great deal on these, though, and considering these were valued at around $200, I figured that couldn't still be the case. Unfortunately, it was still the case, but I can see how any airtight earbuds would have the same problem.
If there's no music playing while the buds are in, I can hear myself breathe. If something touches the cable, or the jack, or if you tap on the buds while they're in your ear, you can hear it. It's not just a noise, it sounds like it's coming from inside your brain, like someone is tapping around in there. Plug your ears with your fingers and listen to yourself breathe, swallow, cough... blink. That's what you'll hear with no music on. Now plug your ears with your thumbs and use your other fingers to tap around your head. That's what you'll hear when the music's playing.
As annoying as that literally sounds, you somehow forget all about it. Granted, that takes some getting used to, but when I get my music going and start getting my lift on, I pretty much forget I'm wearing these and it's like the crystal clear music is coming from an unknown source.

The sound quality is great, the earbuds block out noise and it's like they turn your head into a little soundproof chamber in which to bounce music around. Low ranges are clear and defined, they don't just sound like thumps, you can hear the varaitions in deep tones. The mid and high ranges aren't overbearing like with most earbuds, even with the volume turned up very high. You'll rarely need to turn the volume up very high with these on, though, considering the only reason to do so would be to block out other noises. The airtight buds do a great job of that, which allows for good low-volume listening, but during workouts, when your breathing gets heavy, you may end up hearing more of yourself than your music. I've found that turning the volume up a little more takes good care of that.

The only thing I have trouble getting over is the cord. It's pretty short. I have to wear my shuffle at the neck of my shirt or, at the very farthest, the sleeve, as opposed to my waist, which the ipod earphones allowed for. These come with an extension cord, but I wouldn't wear it during my workouts because I'd hear anything touching it from the jack to the earbuds. The short cord can get in the way of my workouts if I turn my head too fast, because it can pop one of the buds out. It doesn't sound like a big deal, but it actually hurts a little bit. Stick your finger in your ear and pull it out fast or flick it out. That's what taking the earbuds out too fast feels/sounds like.
Even though I took a lot of time describing the problems I had with these earphones, they're easy to forget about and are made up for by the quality, comfort, and isolation. As workout earphones, they are totally worth the price I paid. Would I pay full price for them? No, but if I was the type to pay full price for everything, I wouldn't be on Amazon.

Comment: I've been in the market for a new pair of in-ear headphones and have tried a variety of options before coming to the Denon 751s.

I had Sennheiser CX300-B Earbuds (Black) for a while which were a fantastic pair at an even more fantastic price. Easy to listen to, definitely not the most accurate, but for $20 they were an amazing upgrade to the iPod headphones and were simply great for casual use. They also had the silicone tips which are effective for blocking out sound on a subway or airplane without needing "noise canceling" technology.

Okay, so I needed to upgrade from the CX300s and decided to go forward to a pair at about $100. I'd heard great things about Etymotic headphones, so I tried the Etymotic Research ER6i Isolator In-Ear Earphones (White). This was a terrible decision, though they claim the "i" in the model number is a specific impedance adjustment for portable devices like the iPod, they really sounded terrible. They were also not particularly easy to insert into my ears. I tried all the different fittings they included but to no avail, I never had sufficient power or bass response.

Anyways, I moved on to yet another option... one I knew would be flawed from the get-go, the Bose® In-Ear Headphones. I picked those up from a BestBuy to use on a trip to Boston and figured I could return them later. Bose really does a mediocre job at an elevated price. Over-hyped everything, I wasn't even sure what I was listening to at times. I'm an audio engineer and these really didn't do the trick for me. They also didn't really sit in the ear very well, half hanging there, which didn't create a proper seal for good bass response.

Finally I arrived at the Denon 751s. These have a similar style silicone cup to the Sennheiser in-ears I've always liked, but a much higher-quality build. They have a sort of aluminum chassis which is strong and feels nice. A slightly odd thing about them is that the main cord is quite short, perhaps to use as for a necklace-style mp3 player if you are a Japanese school girl, but as I'm not, I use the included extension cable as I'm sure everyone else does. I feel like they should definitely create a standard length version of these as opposed to needing to use the extension, but it's really not that big a deal.

Another issue was the packaging. Standard frustrating plastic which makes you almost not even want to try opening it. I know this is just like 90% of other manufacturers, but come on.

Now on to the good stuff. They're comfortable, I use them on the street, in the subway, on airplanes... really anywhere. They provide a clear and balanced sound. Though I sense the high-end a bit accentuated, it's really not bad. They're a pleasure to listen to. They come with a convenient little carrying case which zips up, though I only put them in this if I need to throw them into my backpack or something. At times when I'm walking they can make an annoying sound from the physical pulling of the cord on the earpieces, so I'm not sure they'd be a good pair for running, but it's usually not an issue for me.

The main thing here is that they're well-built, and a great value... As you've read, I've tried a few options in the similar price range and was unimpressed until listening to the 751.

Cheers, and I hope you enjoy them. Follow me @orestimusic on Twitter if you wish.

Comment: JB's review seems spot on. The actual drivers themselves are the same as the AH C700s. These are some amazing ear phones but the burn in period is ridiculous. Never before have I really believed in burn in. 20 hours is just getting started. They will drastically improve past the 60 hour point and then more so. To burn mine in I used a 20 min pink noise clip, alternating with a 1min clip of silence.

I also agree on the supplied tips, I could not get good sound out of them. Thankfully I had some other tips on hand. The Sony EX silicon tips are an excellent match for this earphone, and I have heard some good things about the Comply T400 foam tips. (The Altec Lansing UHP-336 had terrible tips too, I have to wonder about manufacturers supplying such mediocre tips for such expensive earphones.)

The build quality is great on these, very solid earphones with a durable machined aluminum housing. The cabling is not flimsy. I would expect these to last the long haul, but we will see. The cable without the extender is pretty short, I guess it gives the opportunity to use the earphones with clip on mp3 players and such. With the extender I almost find it a bit too long. But I can't complain about such an insignificant detail.

With the price having dropped to $75 and under, I think these are a steal. You just have to keep in mind that they do require some patience in the matters of burn-in and finding a good fit. You will not be disappointed if you give them a chance.

The denon sound signature is fun- it does not sacrifice bass for clarity and detail. Having forward mids, imo, allow one to pick up every whisper from voices. And the top end is sparkly, its magic. Even if I do eventually upgrade, I will keep these babies around.

Comment: These are the best in-ear headphones I have tried to-date, but I do have a couple complaints about them.

First, the positives:
(1) Sound. I'll preface this by saying that I'm not a knowledgeable audiophile, but I use headphones routinely during my commutes to and from work, and definitely appreciate full and rich audio. The sound from these headphones is great, but as others have mentioned, they do require a burn-in period. The bass is deep but not distorting, while high and low ranges remain stable and clear. The headphones convey the depth of music, and it's more like a live performance than the flattening effect that many other headphones produce.

(2) Construction. They are solidly built: the aluminum casing feels strong and protective unlike the cheap-feeling plastic that many other headphones use.

(3) Earbuds. The standard buds that came on the headphones were perfect for me. While the correct size varies from person to person, I found the buds to be the best I have ever used to isolate sound while not creating an underwater feel.

Negatives:
(1) The connector. I have a big beef with the connector that lengthens the headphones. First, the headphones are virtually unusable without the extension because they are so short. If you're using an MP3 player like I usually am that is either in your pocket or bag, you have to use the extension. Because the headphones are virtually unusable without the extension it begs the question of why Denon created the connector at all. My next problem with it is that it is very heavy, and when you are walking with the headphones, you can feel the pull on the earpieces. I've managed to solve this problem by tucking it into the top of my jacket or some other piece of clothing to support it, but it is annoying that Denon didn't adequately consider this.

(2) The case. While the small case for the headphones is sufficient to do the job, Denon sure didn't try very hard with it. While this isn't a huge deal, for the money, I expect better.

**Update: The shortened headphones without the extension actually serve a useful purpose (who knew?!). I've been using them recently without the extension for running. The cord is just long enough to connect to an armband without restricting your head movement. They actually work great for running; there is no extra cord length to mess around with.