Full review here:
http://www.head-fi.org/t/664229/review-inear-stagediver-series

I like the IE 800. I like *uncomplicated* earphones, those you can easily insert without searching the perfect fit to quickly enjoy music. I'm a fan of the build quality and the nice leather pouch. The earphone sits hardly noticeable in the ear canal and the sound is airy and effortlessly reveals smallest details from its digital source. Yet the small housing blows out an incredibly strong bass that distracts but not overshadows. Sonic flaws can be reduced by low volume.
 
However, I cannot accept the IE800 as reference. Introduced as in-ear alternative to the big HD 800, officially marketed as high-end product, it falls short of expectations.
Sound is *special* and thus personal opinion plays a huge role. But compared to some other (cheaper) in-ears, I think the performance of the Sennheiser is inferior (especially treble). I highly recommend to audition the product prior to trusting the big brand name.
 
Comparison review: http://www.head-fi.org/t/664229/review-inear-stagediver-series#post_9443353
 
Detailed review (in German): http://www.hifi-forum.de/viewthread-211-542.html

My first impressions were simply horrible! The bass quantity is way too much.
So in the following review I will have equalized the iPod app in iOS 4.3 with the "less bass" option.
 
Build quality: Rubbery plastic, fake leather, fake chrome made out of plastic, ... typically made/designed in America! Nice looks at first, but cheap materials on closer looks. The design is a cross of Phiaton's PS320 and Bose's On-Ear. It's not too bad, but it's still very far from anything high quality or luxurious.
The cable feels nice and the plastic buttons on the remote respond well.
My only two actual concerns with the design are that the earcups don't rotate far enough (they remain bent so that your ear has more pressure in the back) and that they're not foldable (the cable is two-sided, Klipsch could have easily added some more joints, really).
 
Bass: Uncontrolled, echoed, bloated, rumbling, extends even to the higher mids, ... IF not equalized!
However, if you take the bass by the balls and bring it down on its knees, you will have a nice musical thumping bass with nice punchy impact that extends very deep.
But again, I must warn you! If your source does not provide an equalizer, stay away from this beast! The bass rumbles. A lot!
 
Mids:The overall sound has a great energetic feel, similar to that of the Panasonic RP-HJE900 in-ears. Even though recessed, guitars sound powerful. (Especially female) voices are crystal clear and are highly detailed without being too sensitive about production quality. I'm not saying that RHCP's Californication sounds good, but the body and richness of the sound can overshadow a few mishaps. Even though definitely not designed for that purpose, the Image One does offer adequate analytical capabilities for the price.
IF not equalized, the bass extends fairly deep into the mids, not only darkening the sound, but even ruining the sound of electrical guitars: Dear Klipsch, if you have a song starting with a guitar intro, people do not expect it to rumble! Thank you!
 
Highs: Similar to the medium frequency range, the Image One does a nice job creating a rich and full bodied sound. Occasionally I experienced a small sparkle. On the other hand, I've noticed some high notes were cut off. This is a phenomena I only know by Bose's cheapest On-Ear: cymbals that are supposed to sound like "TS" end up as a flat "SH". This is not often the case (with the Bose always) which leads me to believe that the high frequency graph is not linear at all. However, I hardly noticed any sibilance, which, regarding the extension, is very good.
Luckily, the bass does not affect the highs.
 
Timbre is bad, IF unequalized (sorry, but I can't emphasize this enough)! The overall sound is too dark and the low mids and bass are a rumbling mess without any chance of instrument separation or recognition. Maybe my ears are a little too touchy, but even with the iPod equalizer settings set to "less bass", quantity surpasses that of the HFI-780 - it's really that strong.
Equalized, I really enjoy the overall sound presentation. Timbre and soundstage (the sound has a nice amount of air) are good for the price.
 
The remote works well, calls are a little too quiet (but the volume buttons are easily accessed) and the mic is alright. It's nothing worth rewarding, but it works well, both with the iPhone 3GS and 4.
 
To conclude, my main gripe with the Klipsch Image One is the killer amount of bass that has an awful powerful rumble. I've had an eardrum perforation once and I can say that the Klipsch sounds exactly like that! Why I would pay 150 € for a boxed version of a default is beyond me!
Luckily, the Image One does have potential and it just needs some help to get into that direction. A fun and rich sound awaits the durable eardrum. Fans of high fidelity will be ashamed by Klipsch for the mainstream youth product that's been thrown on the market, even more so by the popularity.
Sources that do not provide an equalizer should stay far away!
 
Value: 2.5/5
You get a decent headphone, average build quality and a good enough headset.
Audio Quality: 1.5/5 unequalized, 4/5 equalized
The rumbling bass is just way too much. It has the most amount of bass I've ever heard.
Design: 3/5
Looks are good but some decisions, like the earcups or missing joints, are confusing.
Comfort: 2.5/5
A lazy copy of Bose. Pressure on the ears is awkward and the soft cushions still manage to crease my ears.
Overall: 3/5
The Image One is fairly new and it's on sale already. Looks are good and sound can be very engaging. The high resolution and strong presentation make a great couple. I also value the headset.
 
Price paid: 69,95 + 5,95 € (new)

I got these for cheap and they were my first pair that I didn't buy randomly. I read a review in which they were praised as a great IEM, even for the launch price of $ 150. Turns out Sennheiser bribed the magazine (there's no other way)!
 
Comfort is okay, the cable feels good but is highly microphonic. Even wearing the CX-500 over-ear doesn't help enough.
 
Audio quality is all muddy bass. There's nothing to it. A warm sound, exaggerated bass, colored mids, bad highs ("Tsh" instead of a "Tz" sound with hi-hats), poor resolution (everything is smoothed out), no soundstage.
 
That's it. The CX-500 in a nutshell. Avoid if possible. (This review is based on the € 30 I paid new for it. If I had paid anything above € 50 I'd hate myself! And yes, I'm 100% sure I don't have a fake. I got it from an official reseller in a store.)
 
BTW, the only difference of the "G4ME" edition is the even more ugly plastic chrome look. Why they charge even more money for the uglier "G4ME" version is something I'll never understand.
Just, simply don't... they give Sennheiser a bad name (and for me enough reason not to trust this brand again)!

These were recommended to me in the forum when I was searching for a "warm comfortable IEM". Eventually I got them from the sale/trade forum in a "like new" state.
 
The build quality is quite poor on these. The dirt filter on the left nozzle was misplaced slightly, not fully covering the nozzle. This could be easily fixed by slightly elevating it with a needle. Also, one of the bass filters came off (or was never fully on) which is also very easily fixed. However, it's recommended to take a thorough look at them before trying them out, as especially the loose bass filter produced a very awkward sound.
The metal body and the stiff cable seem like they'll last for a very long time, though.
 
Initially I also had huge comfort issues. The screwable bass plates touched my ear which is very uncomfortable and after some time even hurt. The included silicone tips are too hard, in my opinion. Thus I've replaced them with an easy DIY foam mod. Rarely, the plates still touch my right ear, but it's nothing major and can be prevented when wearing the cable over-ear.
 
At first I had a very hard time adapting to these as I'm used to the Ultrasone HFI-780. The warm sound signature and strong boomy bass of the Hippo was very unusual to me. Meanwhile, I think they're a great addition to my collection and I wear them every night at very low volumes.
 
I'll make this short as this is my third review today: These IEMs are awesome with Hip-Hop/Rap, Electronica and Rock. Bass is a treat (punchy and boomy at the same time, slightly bloated - extends just slightly into the mids but very fair for the price), resolution is great and soundstage is amazing for an IEM. The highs extend far enough and are very sharp (in a positive way). Incredible value for the price!
 
This IEM is pure fun and not recommended for analytical listeners as the sound is colored and slightly too dark.
This is a great back-up IEM. Sadly I can't fully recommend it as first choice because the sound signature is a liitle too far on the "fun" ("musical", if you have to) side.
 
Hippo should invest some bucks in a product designer for future releases. The overall design is nothing but practical and the "hippo VB" prints already look like fakes.

The Bose was a gift from my wife, which, at first, I gladly accepted. But the sound dissapointed after some while.
 
Putting these on my head, I couldn't believe the comfort. They are very light and the ear cushions are soft as a cloud. The ear cushions somehow suck onto the ear resulting in a better isolation than with some IEMs I've tried. I've fallen asleep many times forgetting I'm wearing them. I also wore them in loud places without having music playing. I then noticed the strong microphonics which are actually rare for a headphone. It's not the cable, actually, but your very own foot steps. However, it's not an issue with music playing.
The also fold up nicely and the included pouch seems robust enough. I count the looks as a plus, too.
 
The first thing that you'll notice with music, though, is the strong bass and the warm and smooth presentation. The bass has its very own signature and it's difficult to compare it to other headphones as with the Bose it seems to be a completely different dimension. It's very boomy and dark. I guess it works well with Pop but fails with all other genres - at least from a hi-fi perspective.
The rest dissapoints completely. The mids are taken in from the bass (Corinne Bailey Rae's voice sounds way too dark and even vibrates like coming out of an uncontrolled subwoofer) and the highs seem like they're cut off. Hi-hats sound very annoying as a "Tz" sound results in a "Tsh" (like it's also the case with Sennheiser's CX series). There's no soundstage at all (the sound is projected right into your ear without even trying to be anything but flat) and the resolution is very low. You will definitely not hear new things in your music that you haven't heard before!
Also, the sound is very colored. It's very difficult to tell an acoustic guitar apart from an electric guitar.
 
Many people critisize the build quality, but I'm not one of the people that throw their € 160 into a bag so I didn't have the slightest issues.
 
Short, if you feel comfortable paying $ 150 for comfort, which I'm sure many non-head-fiers are, you'll be alright. But if you want to enjoy music, like emotion in voices, prefer the bass to be precise or have any music with highs then stay away!
I just hope that other brands copy the portable design as there's no portable headphone as comfortable in the same price range.
 
Compared to other 'phones though, the Bose does actually sound much better than the AKG K450 (another failure) but has absolutely nothing (sound-wise) on the much cheaper Hippo VB, for example. Nothing!

I really love these 'phones due to their bright sound, extended treble and punchy bass.
The frequencies range from a very deep sounding sub-bass to almost harsh highs, which to me sound very sparkling, though.
Whenever I wear these headphones I never have the feeling that the sound is altered and they feel very natural to me. With warmer sounding cans like the Beyerdynamic, I have the feeling that I cut myself from real life and I can easily tell if somebody is talking to me. With the HFI-780, outside noise could just as well be part of the record - I couldn't tell the difference with people speaking in the same room (with live recordings anyway).
 
I ripped my eardrum open last year, that's why I decided in favor for Ultrasone's products and their S-Logic (Plus) models that do not send the waves directly into your ear but actually onto your ear, which creates a more distanced sound. My doctor said, however, that earphones can never be as loud as to damage the eardrum so in my case, at least, S-Logic is but a sound preference.
ULE metal shielding sounds fancy and it's slightly calming to know it's there, but in the end it might be just another gimmick.
 
However, the S-Logic sound makes the music sound much further away. In case of the HFI-780, soundstage is great and separation of instruments pleases. S-Logic seems to be a "love it or hate it" kind of thing and in my case, as I love it, I have a very hard time to adapt to IEMs for portable use.
The sound signature is mostly recommended for electronica and other electronic genres of music. However, I'm very pleased with the sound when listening to Neo-Classical (violins especially because of the sparkly treble), Vocal (great resolution) and Rock (punchy bass is magical for kick drums). Ironically, I mostly listen to Jazz. Although soundstage and timber get the most out of great recordings, the overall sound signature could be warmer for Jazz and the bass boomier for sub-genres like Lo-Fi, Ambient, Jazz-Fusion, etc. But as soon as a high note kicks in I forget about that!
 
I've often heard that people think the mids are recessed and bass is too strong. I can't agree at all and also looking at the frequency graph I can't see why people think so. The DT770, for example, has way(!) more emphasis on bass than the HFI-780.
 
Speeking of Beyerdynamic, comfort is a field in which Ultrasone as a lot to improve in. The majority thinks that the pads are too stiff and thus the pressure is uncomfortable. I have a small head and I can't agree. However, the headband is too big for me, so that I've put a piece of cloth between the headband and my head to prevent the pads pushing my left ear down. Others say that the headband does not extend far enough. Everybody says that it's not comfortable enough.
 
Like I've stated before, this is a love it or hate it headphone. Personally, I've fallen in love on day one and I don't see me switching to another brand anytime soon. I'll eventually upgrade to another model because of comfort issues, but soundwise I'm fully pleased. Personally, I think this is the way music is meant to be heard. I really can't speak in favor of darker sounding headphones because the HFI-780 nailed the sound of a violin, which is my favorite Classical instrument.
 
Edit/Update (03/2011): I've had the HFI-780 for almost two years now. Naturally, with increased experience and testing of different models, my perception has changed or evolved.
As for what I thought was a great timbre, I still do think it's appropriate for the price level, but it's definitely not it's strong point. Once you get used to the HFI-780, instrument separation is easy and instruments sound natural, but if you switch headphones often, the timbre might be lacking a little authenticity.
Meanwhile, I am a bit bothered by the recessed and flat mids. It's not a biggie, but something that will grow apparent after some time.
As for the comfort, I have replaced the headband's pleather with an Ultrasone velours strip, which improves it a lot.
Finally, these are still a great set of cans, especially for movies and I couldn't find a better headphone for the same price.