The C710 are also $83.99 at Beach Audio.
Denon Ah-c710k : Headphones
Having had both the C710 and RE0, I would say go for the Denon even at the $99. These would be the opposite of the RE0 with a lean toward the low end/mids emphasis and a larger soundstage.
The new design is nice. Reminds me of the UM2 how they just pop in when using silicone tips. The come with one pair of Comply T-400 also. Quite rubbery sticky tips that give excellent isolation. Very good canalphone isolation and similar to the Westone with silicone. The mouth of the tips is very wide same as the Sennheiser tips which helps with the image size. I do not like other tips and think the stock tips are the best for them.
They are pretty huge. Not counting the tube the housing is 15mm long and 12mm thick in the larger center portion housing the driver. They will fit easier than a Shure or some other large body earphones but they stick out. From pictures it would seem that they will certainly stick out less than the C700/751 though and also less than UE's first design does. Very comfy and secure fit though. A very thin light cable with a Y split that is one foot after the plug then two more feet to the earphones. This does seem to help with the microphonics. The cord draw is more useful to keep the phones from tangling since the microphonics increase with the cable tightened.
Some thoughts a few hours out of the box. So far I agree with HONEYBOY about them being sensitive. An impedance adapter is recommended for something that hisses. I have tested with one(the P->S) and it works well. First the .7 meter cord becomes a nice length with the adapter cable and the impedance is low enough. Or keeping your files at 89dB gain should work well. I have 4 players, three don't hiss and the other has gain control within the custom EQ so hiss can be controlled.
I also agree that they have nice detail and some high quality mids that are slightly forward. The treble is well controlled but I don't hear so much treble energy. Less than a Phonak or RE0. Less than an ER4P/S or CK10. The treble(out of the box) is nearly identical to the AI-M9. Quite apparent, out in front/not laid back on the high end. Not extended as an RE0 or a Triple.fi is on the high end. They might be more "aggressive" only versus IE8 or FX500. I think on the whole spectrum they are in the middle with some phones being more aggressive and some not. I find them just enough to be lively but still warm, smooth, and well behaved/not crossing into harshness or sibilance.
I don't really agree with HONEYBOY that these are not for everyone. Of course any earphone will not be for literally everyone but in the context that these are not strictly in one camp or the other but in the middle. These are not PFE/REO/ETY/ADDIEM nor Atrio/EB/FX500. I think the C710 will please a majority of the people. The price is good. They do well in trying to mimic a headphone sound with good handling of reverb, good imaging/distance cues, and a big sound. The bass is strong but extremely well behaved. I think it will be enough satisfy those who like more bass but it is handled well and still won't offend those who prefer neutral. The treble is evident and detailed, neither very extended or rolled off that much, which being in the middle will satisfy more people than not. I also think everyone will like the mids which are just forward enough and some of the best and good with both male and female vocals. I would make an earphone like this if I wanted it to appeal to the most people. Good at everything and not too much/or too little of any one thing.
I'm off to use them a bit and get some more burn in on them.
So far:
The Pros
-Really good sound and looks, good fit and comfort.
-Nice build quality.
-Good accessory pack.
-Good price( in the US at least).
The Negatives
-Cord length(.7 meter plus .8 meter extension). Might depend on preference for length and the added weight when/if using the extension can bother some.
-Cord tangles more than other earphones.
-Hiss may be a problem depending on source
Here is one other review that comes up on Google.
Denon AH-C710 earphones review - Digital Lifestyle - Macworld UK