I want to share some thoughts on the IE900 after almost two weeks of daily use. I’m sorry to say I’m not sufficiently technical to address in a way that many look for, as such, it will be a layman description with the knowledge I do have where possible. I am a music lover for many years (and once upon a time 90s DJ...) and up till last year, mostly listen via my separates systems and a variety of headphones and earphones - as of last November, I didn’t even know what a hybrid IEM was, let alone a single DD or an EST driver, they were all just earphones, headphones and some were Bluetooth (of which I've a few gathering dust)! My journey over the last few months with IEMs has certainly been obsessive, expensive and incredibly enjoyable - I’ve heard music in ways I’ve never before and I now rarely listen via my main system or full-size headphones. I admit to being a fan of Sennheiser and have had a few of their products over the years - HD-25-1 being a go-to back in my DJ days, HD650 (which I never use) in more recent years and a trusty set of IE8 that served me well for about 8 years, only actually finally retiring them last year as this hobby took hold. I’ve learnt a lot (but not enough) in the last few months and met many great likeminded music fans, I plan to continue this voyage of discovery and strive to be more proficient to articulate what I ‘hear’ into words that are useful to others… but for now, this is about as good as I can give!
Most home listening has been via the Sony NW-WM1A or Sony ZX500 for out and about portable use.
My recent IEM collection in order of purchase: XBA-N3, DUNU ZEN, DUNU SA6, Sony IER-M9, UM MEST MKII
First and foremost, I absolutely love the IE900 - right now, if I could only keep one of my IEMs, it would be this - mostly due to being the most solid all-rounder of any IEM I’ve heard in terms of its ability to handle any genre. In addition; the size, weight, form factor are perfect for any situation - walking, in bed, wandering about the house etc. I walk 5k every morning with my dog and I look forward to getting up at 6am to get these popped back in my ears - likewise during the day while working, finding moments to get lost in the music for a few minutes, even just while making my lunch or getting through some admin that doesn’t require much brainpower. I keep looking at others in my collection and thinking I must give them a shot, but then nah, IE900 it is…
Soundstage feels wide and natural, a well-positioned ‘stereo’ sound, instruments very well positioned and where I expect to find them relative to general listening experience of music over the years. The MEST MKII in comparison is somewhat wider but absolutely ‘taller’ too and much more 3D - this is good for some music but definitely not all - for example, I love it on well recorded ambient music, especially very cinematic albums - I’m not as keen with a lot of rock albums though, I find it can sound a bit unnatural at times, instruments a bit off in terms of positioning - a thought though in this regard, is it just I’m not used to hearing a delivery of this nature and need to get used to it?! But on MEST with genres that suit, that 3D tall and wide delivery is stunning and certainly a keeper in that regard.
In spite of the wide soundstage, I still feel a very centrally focused low-end delivery - I feel like the focus zone is in the middle of my head but separating out as appropriate for the instruments. I actually love how it ‘sits’ in my head, I really feel with kick drums for example that they thud in both ears perfectly to land a central delivery… reminds me of beat-matching kick drums back in the good old DJ days and I actually crave this position with other IEMs at times.
Some of my test tracks had deep sub bass sitting alongside pounding kick drums - all wonderfully controlled and I keep wondering how the heck something so small is capable of this. I find the bass more obvious compared to the MEST MKII, not sure if its better per-say - I think going back to my reference to its position is where it shines - potentially a personal preference as opposed to one being better than the other.
The higher register of treble is an area that I tend to shy away from in music delivery - often choosing with audio system over the years to EQ bass up and treble down, probably the techno/house DJ in me. I’ve been concerned about this and look out for comments in reviews when considering purchases that might suggest an IEM is bright. Much to my surprise, yes the treble is more evident than I would expect to like, it feels like its fine-tuned marginally below a point where it could be an issue, but instead sounds wonderful and adds so much to a detailed, pristine and analytical delivery - I’ve yet to find it harsh on any music and again, often amazed how there is so much detail from a single driver.
There is a sense of being slightly recessed vs the MEST, a more forward centre on the MEST for sure which means for some vocal tracks, especially male vocals on the lower end of the scale that they can feel slightly back - not to the point that it bothers me personally but I do note at times.
The cable is excellent and very similar to the IER-M9, looks almost the exact same - slightly stiffer though and a small amount of microphonics if not correctly positioned around my ears and with the chin thing (what’s it called?!) - but easy to position and when out walking, I get zero cable feedback. The ear hooks are quite stiff and bend well around my ears - a slight concern here is when bending them over my ears, I wonder is this putting strain on the MMCX connectors that might damage over time?
The tips didn’t work out that well for me, I couldn’t get a good seal with any of the silicone tips and they sounded pretty poor as a result - I tried them first and was incredibly underwhelmed, bass was absolutely feeble as best. Switched to the included large foam tip and a whole new world opened - wow! I did ultimately switch to Comply TSX-500 in medium as I get an even better seal and no impact to SQ, unlike with some others where bass becomes way too much and overall too dark, not the case here at all - the TSX-500 seem to have a relatively medium bore size. Isolation is great - when walking, I can hear louder traffic but not enough to interrupt my listening, at home sitting in my kitchen as I am right now, I can’t hear any other noise in the house, including my wife talking to me… is it terrible to admit my frustration with having to unplug an IEM and ask my wife to say whatever she said again, only to find its a reminder I need to cut the grass or something? - she should know I have important listening to do.
They are hungry enough compared to the MEST MKII, on the Sony NW-WM1A, I need to crank up to the late 50s (out of 120) somewhere on high-gain, versus maybe early 40s on the MEST. Still plenty of room though.
Anyway, I would struggle to say whether I prefer the MEST to the IE900, they are both incredible IEMs in their own right but as noted, the IE900 would probably take the prize given how they can be a jack of all trades with any genre in any listening situation. I’m not exaggerating when I say they often take my breath away, I’ve stayed up way past my bedtime several nights over the last couple of weeks as I just want to keep listening, I’ve even broken my no wine during the week rule and had to pour a glass to accompany my listening bliss! They definitely complement each other well though and I will certainly be submerging myself in the MEST again soon for longer sessions.
They are unbelievably addictive and in my humble opinion, absolutely worth the price tag. Apologies again that I can’t address areas that a lot of folks here would like to know and I hope this was somewhat useful. I’m conscious there is a lot of interest in this IEM and I’m very lucky to have one before launch, as such keen to share what I can. Still early days too but I do feel comfortable at this point with my findings.
is impressively active! I’ll inquire about which stage of the roll out Greece will be able to make IE 900 purchases, but for now I do know that they should be available globally at least by July. Sennheiser has a lot of stuff to make, so we have to thank you in advance for your patience. Hopefully you’ll be able to join clubIE900 before you know it!
a very old audiophile veteran? 
but it seems like he has quite the collection without bragging about it. He seems to subscribe to the idea of buying whatever sounds good to you, without getting too hung up on the opinions of others. With that said, with his broad experience, I do wish he would write some Head Gear reviews 
