Sennheiser IE 900: Fun and Technical!

A lesson learned

Diving into this hobby, I was under the impression that getting the absolute “best” [insert gear] component would naturally result in the “best” possible sound (at the time it was the RME DAC / THX AAA 789 combo) respective to their price. Well, I’m glad my curiosity helped me realize the mindset that I had was naive, closed-minded, and stupid. I’ve come to learn and accept that everything matters in audio. Food, fashion, cars, sports, anything really all have little aspects that improve the overall experience or performance. From the presentation of the food to the quality of the fabric to the minor performance tweak, and to the top-notch equipment they all add up, oftentimes not immediate or substantial but worthwhile in the long term; I think audio is no exception. The DAC, the amp, and whatever goes in between (yeah, y’all know what I’m talking about) all feed into whatever transducer being used. Sometimes you get stuff that just “clicks” (great synergy) and sometimes you don’t. This is probably not something that needs introduction in certain (and rare) places/forums but I think it’s always a good reminder nonetheless. The key is long-term enjoyment that is built upon a desired sonic strategy (the system as a whole), not instant gratification rooted in impulsive hype (individual component upgrade syndrome). That’s what it is for me, at least. The degree of importance is going to be different for each individual, but the bottom line is that source gear is crucial as is the synergy created by it. Not chasing after synergy is probably the biggest mistake I’ve made in this hobby, along with ignoring to view the system holistically. This article features my personal experience with the 900 along with a lesson learned and as such, I hope some of this will be useful.

A little about myself

I primarily listen to j-pop and soundtrack music (vocal and instrumental heavy). Sometimes classical, rap, R&B, rock, jazz, and whatever I find interesting. I’m also primarily invested in headphones, so I’m not very experienced with IEMs. Headphones in the collection include Sennheiser HD6XX, Hifiman Sundara, ZMF VC/Aeolus, and Focal Clear/Utopia. In addition, I do prioritize a more organic neutral to slightly warm but dry kind of overall intimate signature. However, as long as the signature is done well and is engaging enough, I’ll probably come to like and appreciate it. So, please keep these in mind.

I’m just writing this for fun and thought it would be a useful piece of information to share, despite the myriad of “reviews” already out of the 900. Everything mentioned here I personally own and I think it’s worth mentioning, don’t take this article too seriously.

Chain used

The much over-hyped Holo Spring 3 KTE DAC via USB…
Balanced out into the never heard of Allnic HPA 3000GT tube amp…
Inserted via balanced to the “not-an-HD900” Sennheiser IE 900 IEM…
Just some regular Spinfit CP100+ tips

Yes, I am very aware that this chain is just a bit unrealistic to use on an IEM. But, hey, I think it works pretty damn well and I wouldn’t spend time writing about it if I didn’t think it was worth doing. So, to the very niche group of people running desktop gear for IEMs, this is for you (lol). To be clear, I do not think it’s an effective use of money to acquire gear in this range to use solely for an IEM. But, if you already have gear like this for some TOTL headphones, then why not?

Sennheiser IE 900

TL;DR [Fun yet technical] A pretty coherently natural-sounding, well-balanced IEM with very good extension on both ends, a tasteful boost in the low-end, and a forward treble overall while being a pretty good value on top of scaling quite well. Bass is this IEM’s strength with very good texture, grip, organicness, and definition. Midrange can have great balance depending on the pairing but does favor the upper-mids slightly. Treble is quite extended and forward overall however, I wouldn’t call it bright but energetic. Timbre is natural, tonal density is adequate, imaging is pretty precise, dynamics (both macro/micro) overall is quite good, detail punches above its price, and staging focuses more on width rather than depth.

Treble: So, this aspect of the sound is actually quite interesting and perhaps the pickiest part of the 900, but it can potentially be very rewarding as well. Overall, the treble is presented very forwardly and extends very well, but I do not consider them bright.

Without taking source gear into account they will, for the most part, sound quite intense and, in addition, some sibilance will pass through. Tip-rolling will probably help tame this part of the 900 but with the tips I’ve tried, none of them actually got rid of the intensity and lack of control. It was always somewhat there and can be potentially bothersome depending on the person.

Now with the chain I have hooked up to it, the treble on the 900 significantly shifts from sounding intense to something more refined. Although the overall treble here is still very much forward and energetic, it maintains a sense of refinement and control. It’s actually reminiscent of the Utopia IMO (not in performance) in that the Utopia’s treble sounds underwhelming, whereas the 900’s treble sounds overwhelming on improperly matched source gear. So, both are picky in this regard. In summary, I feel that the treble on the 900 is raw yet somehow refined. Sure, there may be other TOTL offerings that share this quality, and it’s not uncommon (in the hi-end) to have this level of refinement but, nonetheless, this is still very impressive for an IEM of this price (at least to me).

Mids: This part here is pretty straightforward. No bueno source gear equals recessed and sucked-out mids. Well-matched source gear equals a neutral and pretty natural-sounding midrange. It’s well-balanced throughout, albeit maybe favoring the upper mids slightly. In addition, the 900 also has very good timbre. Tonal density is also good here and is neither overbearing nor lacking in quality/quantity. Really, I have no complaints in the midrange department other than wanting it to be slightly more intimate; it’s solid overall (with good synergy).

Bass: Now overall bass is pretty much consistent across the gear I’ve tried it on. I’m not implying it doesn’t improve as well but I’m mostly referring to the overall character. It’s boosted to what I think is neutral and it’s very technical consisting of good texture/definition that extends very well. As you might have already guessed, it does improve quite a bit depending on source gear giving it even more texture, definition, balance, and scale while maintaining appropriate levels of quantity and quality without being overbearing (or containing any bleed). So, in this regard, I’d say it’s a standout quality of the 900. If I can only make one criticism it would be that it could be a hair faster but, at this price, it isn’t really worth complaining about in my book.

Other: Spatially, I think it’s actually fairly wide. Depth, on the other hand, is fine but not really a standout. Instrument separation is solid here as is detail. Dynamics are great as well in both micro and macro. Grip and control are largely dependent on the source gear and synergy I find. Again, considering the price, I think everything here is solid and does improve quite a bit when scaled up. Stage depth is probably the only “meh” aspect and in terms of holographicness, it isn’t really. Volume-wise, they’re not that great at lower volumes (not horrible), so ideally they like being played at moderate to slightly louder volumes.

Comparisons: Unfortunately since I’m not as invested in IEMs, I don’t have much in terms of comparisons (useful as it is). So, the basis of most of my thoughts is compared to the headphones I have instead (different as they are). I do own a Sony IER-M9 but I think the 900 is a noticeable step-up over it when taking into account source gear and synergy. The only time I would pick the M9 over the 900 is if I plan to plug them into whatever source gear (ie. smartphone). The M9 doesn’t scale that much in my experience so its character and performance remain consistent regardless of what it’s plugged into. The M9, I think, is still a competent sounding IEM but nothing more and nothing less.

Brise Audio BSEP

I liked the 900 enough to want to get a nice, fancy cable for it so I ended up with a Brise cable. Apparently, this cable was specifically tuned for the 900. There weren’t any impressions on other sites, so curiosity led me to try it out for myself.

To be honest, I’m currently not in love with this cable (maybe over time or in a different system) and I’m not a big fan of how it was tuned. That being said, I can still appreciate what it does and how it can be a great option for other people (assuming you’d like to dive into cables). After taking the time to understand it a bit I do think it’s a great cable, personal preferences aside.

As for sound, these were some of the notes I had taken down…

So treble here is noticeably sweeter and slightly more refined making it pretty pleasing to listen to. The midrange is slightly pulled back tilting the 900 to a slightly more u-shaped or slightly v-shaped tonality. Just to be clear, mids aren’t sucked out or anything. The BSEP tunes the bass to be meatier and denser overall but depending on the pairing, it might be too much for those wanting a more evenhanded bass profile. Across the board, technicalities have also been slightly improved. The main things I noticed were a blacker background, better separation, and a wider stage. Using the chain I have now with the BSEP, there was actually a pretty distracting sibilance. Going back to the stock cable, it posed no problem to me so I’m not sure what is causing this. It could be anything in the chain since I’ve been making a few minor upgrades recently. Anyway, I decided to swap out the tubes on the Allnic for my other favorite pair and that did solve the sibilance issue. Although it changed the tonality of the 900 a bit, it still sounded pretty great to me.

In closing, I think the BSEP is a great cable that further capitalizes on the 900’s strengths. But, its tuning might not be for some.

UPDATE (04/23/2022): Apparently these Brise cables require major burn-in, and I believe it because this cable is damn impressive with the 900. It’s now very well-balanced with great added technicalities. Treble is still sweet with no major problems with sibilance, midrange is now enhanced technically while still sounding very natural, and bass just oozes texture without it being overly boosted. This now gets a thumbs-up from me!

Final Thoughts

I think the 900 is a solid IEM that does fun yet technical, very well. The degree to which it can scale with source, IMO, is impressive. To put it into perspective, with every change that I’ve made to my system in the last few months I’ve been able to differentiate using the 900. I do think the 900 can scale more but this is the highest source gear I have currently. Also, yes, I’m sure there are other IEMs (that I don’t have) similarly priced that can scale as well as the 900 therefore take my thoughts lightly.

To be frank, the 900 overall isn’t really what I prefer tonality-wise (and I didn’t like it at first) but it has been my second most used, surprisingly. It’s not an easy suggestion to make due to its pickiness (guess I got lucky with great synergy from the start), but its high scalability factor alone is why I think it’s worth keeping in the collection. For more discussion, questions, or reactions let’s talk here!