This is the "home" pair of earphones you always want to return to. The fit, comfort and noise isolation are all just right. I'm a fan of the 360deg swivel. Sound is simply phenomenal - very musical, fun and non-fatiguing. It features a typical Sennheiser sound: V-shaped, yet highly detailed and smooth; it can be said to have the Sennheiser 'veil' (because of this sound signature). Forgiving and pleasant. Plenty of bass, and slightly emphasized treble (but never fatiguing). Amazing soundstage and good imaging. This specific sound profile has the advantage that you can listen at above-average volumes, and the loudness is never tiring, always beautifully diffused (unless you go crazy high of course). Very refined, detailed, and SO comfortable. Can be worn for hours on end and you'll enjoy every minute of it.

This is my 2nd Sennheiser product, the previous being the HD 598 SE open-back headphones, and I am very satisfied. This review just gives an overall picture and focuses on the sound, which is just sublime. Another point of note is that these earphones cannot be said to have an audiophile sound - although it definitely has audiophile-grade quality and build - because I understand an audiophile signature to be more neutral, more unforgiving and exact. This leans towards purely music lovers, anyone who can appreciate phenomenal sound reproduction of their favourite music - as the box says, "High-fidelity earphones for sophisticated music enjoyment".

Some might view Sennheiser's IE 300 as a step in the wrong direction for the company with its crowd-pleasing, lowest common denominator V-shape sound. If you merely explained to me what this earphone sounded like, I would be inclined to agree with you. However, after using it for many months, I've been impressed by the flawless execution of a sound signature that I usually do not like.

First, the physical design of these earphones is simply stellar, fitting in your ear near-weightlessly with its stylish, plastic housing. It's not winning any awards for materials, but I honestly think that they're much more comfortable than my Moondrop Starfields which use metal. In fact, they're the most comfortable and isolating earbuds I've ever worn, even beating out Apple's stellar offerings in my opinion. Though, I wasn't a fan of the memory foam earbuds. They sound and feel great in theory, but I could never get a solid seal, so your results may vary. The stock, medium silicone earbuds fit well for me.

My greatest criticism of the build is the recessed MMCX connector. This is likely an infuriating attempt to up-sell you on THEIR balanced cable (which I can't even find anymore). I was able to use my own balanced cable by sanding down the red and black plastic on the exterior of the connector, though this may affect resell value, so I don't necessarily recommend it.

Finally, to talk about the sound, these are very bassy earbuds. They even kick more than many over-ear headphones, to be honest. There is a lot of top-end too, which adds some sparkle that can border on sibilance at high volumes. The more you use it, the more you'll find your volume sweet-spot. All of this isn't for a lack of technical performance, and the raw detail of the IE 300 handily beats my Starfields (which they better for their much higher price). I also find the mids to be slightly recessed. I usually hate this, but it didn't bother me after just an hour or two of listening.

Their timbre is probably the best in this price bracket for IEM's, many of which rely on BA drivers. I find the reproduction of instruments, especially drums, strings, and pianos to sound very natural. This is likely thanks to the IE 300's single DD. Curiously; I also find that this earphone scales with better sources and amps. I noticed a marked improvement in quality between my Fiio BTR5, and my Schiit Magnius/Modius Stack which is not the case for my Starfields.

Given the IE 300's great isolation, comfort, and stellar execution of the v-shaped sound, I think it will please consumers and audiophiles alike. I hope Sennheiser does more like this in the future.

TL;DR: I really like these. They sound great and they are incredibly comfortable, but I wish they had a slightly flatter frequency response.

I picked these up while they were on sale for $200 rather than the regular $300 price. Most of the reviews I had seen suggested that they were really great IEMs, but that there were others that were a better value for the dollar, so I waited. At $200, though, I think they are a pretty great deal. That puts them right at the same range as the HD560s, my current favorite pair of headphones. My goal was to get something that had a similar sound and gaming performance to those but in an IEM form factor. The IE 300 are not really that, but they are still really great if you don't have unrealistic expectations for what they should be able to do.

Regarding the sound, they do still sound like Sennheisers, but with noticeably more bass and less upper mids than I have come to expect. Frequency response graphs are a little misleading, though, as they don't really feel like there is as much extra bass as the graphs might lead you to believe. But it's still definitely more of a V-shaped sound than the usual Sennheiser sound. More bass, but still tight and not boomy or bloated; more treble than I am used to, but not harsh or fatiguing; and still the same level of detail I'd expect. This gives them a more "fun" sound rather than an accurate, analytical one.

The tips, though... I've seen several reviews say that the silicone ones don't form a good seal and I am inclined to agree. I had to use the foam tips to get a proper fit. Final Audio's silicone tips also do a better job if you have some lying around or don't mind buying some. Overall fit and comfort is excellent, though.

For gaming performance, I was hoping these would somehow get around the laws of physics and give me the same sort of open, immersive sound that the HD560s or PC38x do, but of course, these do not do that. They are IEMs, after all. Final Audio tends to do a bit better in that regard, but I hate how those sound, so... Regardless, the left/right positioning is very good and you won't have any trouble figuring out where things are around you, you're just not going to get that same level of "being there" that you would with the PC38x. You might be able to use some virtual surround processing to mimic that kind of feel, but I haven't tried it yet. Who knows, maybe Sennheiser will follow after Sony and make an open IEM/earbud for the best of both worlds.

Finally, these are super sensitive and super efficient, which is honestly a bit of a problem. I usually use a THX Onyx and I have to set the volume to 3-4 (out of 100) for a reasonable volume. Anything louder than that is just way too loud. I can usually put the HD560s anywhere from 10-16, depending on what I am listening to. Even with just an Apple dongle I have the volume set to 4-6. I'm now wondering if there is a less powerful amp that might give me a more usable volume range...

Anyway, these are really nice IEMs for $200. They sound excellent for music and while they don't perform miracles for gaming, they still do a good job there, too. For $300, it's a harder sell, IMO, but if the $200 price sticks, definitely grab a pair.

so after I got this a few mins after I started experiencing the audio cutting in and out. Was not able to swap cable since it doesn't fit the usual mmcx cable. when I move my head audio cuts off so I knew right away I have a defective unit. Good thing I was able to have it repaired and Sennheiser was kind enough to send me a new one. International warranty works. Am listening to my new pair while writing this review. Bass really is the star of the show. I bought this as a replacement for my IE80. It really is good. Hoping the audio wouldn't cut off anytime soon. Thank you Senn Phils.

These are really comfortable as they are small. (although I went with final audio tips as they gave me a better seal and less so with its stock tips).
The wires that goes around the ear has memory in it. I like it, some may not.

These have a bit of a V shaped sound, with increased bass and treble.
It has increased bass but not overbearing. Has nice impact making music more engaging. Bass is not muddy or sloppy it is well done for my taste.
The mids are recessed a bit but it does not bother me as I'm a vocal lover.
The overall sound signature is warm and non-fatiguing.

It comes with a nice pocket sized case with 3 sets of silicone tips and 3 sets of foam.
I much prefer silicone as foam tips irritate my ear holes after a while. I could get good sound from the stock silicone tips but when yawned, moved my head or jaw the seal would sometimes break and the bass completely falls off.

I'm happy with these for the sale price of $200. I think they beat my ikko oh01s and complement my Blessing 2s when I want something more fun and need to wear for long periods of time.