[Prodigus Prime]

[size=large]Sennheisr CX6 Travel IEM Review[/size]


[size=small]Here's what you will be reading about in my review:

1) CX6 Physical Characteristics
2) How it sounded out of the box
3) How it sounded during the 600 odd hrs burn-in period
4) How it sounds now, setting into its final sound signature post 600 odd hours of burn-in period

5) How it compared against post burn-in CX95 and post burn-in CX500
6) How to use the CX6 for optimal fit & comfort
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[size=medium]CX6 Physical Characteristics
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What the CX6 has is a well designed physical structure to sit in your ear & not protrude out - this way you can wear a bike helmet or a cap covering your ears without affecting the sound much, since the CX6 will level with your ear and not be pushed in more than necessary.

The plastic used is very light.....so light that people who associate weight with build quality will never find the heart to shell out more than 2 dollars if they'd close their eyes & hold the CX6 in their hands - BUT, that does not mean that the CX6 is by any means - BRITTLE !!.....It is quite sturdy & rugged although not the best in ruggedness by any means.

Finish quality is very precise, edges & corners have that laser-cut finish quality that you'd come to expect of a $240 IEM.

That said.....lets look at the CX6's WORST physical problem in the picture below:

Doesn't look like a CX6 ?????

You are wrong - this *is* the CX6 after a year of use - what you thought was a high class Brushed Aluminium panel is actually just a brushed aluminium finish on plastic that starts coming off after you touch/brush against the panel about 50 times.

Sennheiser didn't & still doesn't bother to mention this and what I thought would be a Great idea to provide an Aluminium panel to dissipate heat & maintain thermal balance turned out to be a cheap paint job.....Shame on Sennheiser !!

Not that I would not buy the CX6 if I knew this, but I would have made an *INFORMED* decision & taken proper steps to ensure the longevity of the paint job - Now my $240 IEM looks like cheap trash that people wouldn't own if you paid them to !!!

I will never forgive Sennheiser for this besides the fact that most of their service executives or dealers do not even know of this & refuse to help me on it (and they can't too) !!





[size=large]How it sounded out of the box?
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This CX6 is being used with a Creative Zen without bass boost & custom equalizer set to 12-7-4-7-12, reviewing volume '15'.

Right out of the box, the CX6 sounded nothing less than a throwaway price nameless chinese earphone with too much muddy bass - it was PURE NONSENSE. Then again, even CX500 & CX95 sounded pure nonsensical when they were right out of the box.

The bass was loud & really the only frequency you could mostly hear & it was very muddy - you could hear loads of bass, but could feel none, if you know what am saying - not the airy balanced moisturized high quality bass that you feel like air moving against your ears & don't hear much but still bangs your brains - Just the opposite.

Mids were existence, but lacked the density and body & fine detail that makes you hear the phlegm in the singer's throat - low on detail, weak definition, no smoothness, lacking in fine character, no depth.........NO GOOD !

Treble was so minimal, that it was a wonder I could even manage to hear some cymbals - forget picturizing the instrument spacing or the metallic texture of treble ( I tend to picturize treble notes as metallic rods, whose numbers, temperature, structural integrity, fine mirror finish depends on the quality of the treble)

Soundstage was just a fist sized blob on the centre of my skull protruding towards my face from the inside - imaging was precise though.




[size=large]How it sounded during the 600 odd hrs burn-in period[/size]

Really, reviewing an IEM/OEM right out of the box and *Concluding the performance of the Monitors* is ........CRIMINAL !!

After 50 hrs or so with a 10 minute interval every 5 continuous hrs of running - tamed the bass a bit, but did nothing else.

100 hrs - bass remains how it was after 50 hrs but mids are smoother, toned & treble begins to open up - soundstage remains unchanged & Instrument separation almost nil.

100 - 400 hrs : Really, this was the working period of CX6 - way too many changes & way too many times to document. Sometimes the CX6 sounded balanced, for a few hours bassy, few hours like a SONY (too much mids). Really cannot remember the changes, but it fascinated me, it was really an educational period with me trying to picturize how the diaphragm characteristics were changing over time. Neither did CX500 or CX95 or Custom 3's give this quality of changes during their Burn-in periods.

400-500hrs : By this time almost 8 months had passed since 5th Feb 2009, the day I bought the CX6. Finally the sound seemed like it would settle any time. But I'll not explain anything cos I don't want to take anything away from the experience after 600hrs. Let's just say, the CX6 was finally at the end of teenage & on the verge of adulthood !!!!

600 odd hours: My CX6 is a MAN !!!

[size=large]How it sounds now, settling into its final sound signature post 600 odd hours of burn-in period[/size]


Remember the description of the CX6's sound right out of the box? - there is no relation to that sound at all - ABSOLUTELY NONE.

The CX6 is now an entirely different IEM - as different as an apple is from an orange.

The CX6 is now a RAMBO IEM - Powerful sound, tons & tons of power......gut-wrenching, brain cell murdering yet clean bass.

Schiller's Gluck Und Erfurllung 320kbps mp3 track on my Zen sounded like it never ever did - I could feel (not just hear) the low thumping bass beat hit my brain flesh, not hit a point in my brain, but the whole brain. Like as if my skull was empty & was filled with TIGHT, High Pressure bass !!!

The bass had body, depth, precise moisturing and it was moving my ear drum, not hitting it - if you get the meaning.


Mids.......now now now.....how shall I describe - now my *empty* skull filled with bass is also filled tightly with all the mid frequency range instruments & vocals. I could hear parts of the music I never *monitored* before.

I felt like the diaphragm opened up the track to more detail with a magnifying glass to monitor the details - and as for mp3's.....detail also includes compression errors and also the damped muddled quality of CD quality sound as opposed to the supreme quality of records.

The sonic precision was amazing - I could actually analyze the sound of the guitar string being strummed at the moment when the musician makes contact with the string & you hear the cracking sound just before the resonant frequency of the string generates the guitar tune.

Sound of the stick hitting the drum diaphragm just before the drum made its characteristic sound.............and the phlegm in the singer's throat ------ALL OBVIOUS !!!

Treble .........FINALLY !!!.....at last I could finally enjoy the high quality treble. Now, you must understand, the CX6 treble is not about irritating/piercing quantity but fine quality.

All those metallic rods, spikes, ice daggers I associate with treble notes finally reached ample representation in my mind. I could literally touch the treble notes & feel their metallic texture with my fingers & tongue - I'd appreciate more high freq amplitude but the CX6 was not fatiguing at all.

Its so different from CX500's shrieking treble, but not to the level of CX95's treble amplitude - but definitely of higher quality precision & fidelity.

The frequency response of CX95 was & still is the flattest among any dynamic driver IEM in existence - but the sound pressure, density & soundstage body of CX6 is like comparing a pressurized cylinder to a low pressure gas cylinder - the cylinder being compared to the listener's skull !!!

There is no corner in my head that is not filled with wide CX6 sound - to the extent that the soundstage is wider & higher than my head itself, although it varies from song to song & Vacuum tube recording to Transistor amp recording.

The CX6 sounds warm but not to the extent of sounding boring.....its very precise in that department, which I am confident will be bettered in the IE7 & the stellar IE8 (once burned-in)

Unfortunately, I do not have access to a high quality professional record player other than an old Sony - so I am really limited to monitoring low quality CD sound & even lower quality mp3s.

Yet, am keeping things in perspective here - so don't be carried away too much by my description. If you use records with sound recorded using vacuum tube amps - then its an entirely another plane to refer the CX6 with.

In that level - I don't think anything less than Quality Electrostats would do justice to tube amps & records.

Is the CX6 worth the extra money on the supremely balanced CX95???

Its all about perspective :

1) If you want out and out balanced sound across the frequency range, don't buy the CX6 over CX95

2) If you want way more powerful sound with tons of far more sonic pressure & power - the CX6 shoots the CX95 in the head with a shotgun.

3) If you want to feel the bass in your head trying to leak out of your head & make you feel as though people around you might hear it & you can't afford IE7 or IE8 - then CX6 is the one for you as it has better isolation than the open acoustic IE6.

4) CX500 & Bose IEM are like tin cans compared to Industrial machine like CX6 - its all about POWER, POWER & more greedy, shameless disgustingly naked P.O.W.E.R !!!....CX6 gives you the taste of the IE8 at half the price - it really is like BMW 335i giving you an idea of what the M3 GTR would be like !!!

5) Is the CX6 worth the money for an Audiophile? - Maybe, maybe not. Armature driver supporters may not like the bassy sound or the warmth of the CX6, but to me dynamics are the way to go - after the CX6, am never going to even bother about the dry, clinical armature sound - after this, armatures are zombie IEM's to me - detailed maybe, but emotionally dead....probably because of better harmonics range of dynamics & fuller sound compared to cross over loss in multi-driver IEM's !!!

6) One funny thing is that CX6 (IE6 too) makes IE7 sound like a stupid decision - it is IE7 that is not worth the money sitting between CX6/IE6 & IE8 - IE7 does not give you the price advantage of the CX6/IE6 or the Satanic sound of the IE8. So the more sensible upgrade to the 6 series seems like the IE8. So that's one thing I learned after one year & having fully experienced CX6 & previewed IE7 & IE8 sound (not fully burned in though)




[size=large]COMFORT & FIT[/size]

I use the smallest tip on the CX6 - it feels non-existent after 2 minutes. Hallmark of Sennheiser Engineering, really !!

Where the CX95 lugs at your ears, the over-the-ear professional design of CX6 keeps the IEM firm in the ear.........I think every IEM must be over the ear type - the wire doesn't lug at the IEM & pull it out or weaken the air seal.

So when the IEM's are pushed in to the right depth, maintaining a balanced air pressure in both ears - you don't want anything to disturb the precise air pressure balance or game's over !!!

The Denon AH-C751 may have slightly more bass & treble than CX6 as reviewed by cnet (I wonder if this comparison was with a fully burned in CX6 which I highly doubt so) - but the denon WILL pain your ears in an hour, but the CX6 won't do it until maybe 2 days of continuous use .......its that comfortable !!

It take 5 - 6 tracks for me to fully concentrate on sound & forget my body & if the heavy Denon will start irritating my ear at this time - no point in buying it to listen to a few intense minutes as compared to hours of intense music experience with the Super-comfortable CX6.


I lubricate my ear canal opening with a drop of water spread on both forefingers & applied to the ear canals - to provide the instant air seal with the CX6 - you can use saliva for better seal as saliva has slightly adhesive characteristics as opposed to mere water......its all a matter of what crazy stuff you are willing to do to get the best out of your IEM !!!!




[size=large]THE NOTORIOUS NOTCH/CANAL ISSUE!!![/size]

Now this notch as you can see, probably has two purposes - but whether Sennheiser intended both purposes.....I do not know :

1) The notch helps maintain balanced pressure - as your body heats up the air in an IEM ear-canal seal, the air pressure inside the ear increases causing more resistance to diaphragm movement, hence affecting sound quality & performance

2) As you push in an IEM - the pressure increases in the ear as the air gets compressed between the ear-drum & the IEM diaphragm - the notch helps maintain the designed air-pressure (the pressure level CX6 designers intended the diaphragm of the CX6 to work best. Hence avoiding diaphragm damage if you put in your IEM or pull it out suddenly causing drastic pressure changes that might damage the IEM diaphragm permanently.

3) The notch helps provide a pathway to push dirt using the cleaning tool, out of the mesh section as you can see in the first picture in this topic sub-section.


Whichever of these reasons Sennheiser intended for the notch/canal - both are applicable as far as my experience with the CX6 goes.



I may have forgotten a few details - I'll try address them as & when they are pointed out.



-PEACE

 

[KLS]

Hi prodigy techus, very detailed writeup! Glad you like them

So, other than the IE series (especially IE8), Sennheiser dynamic-IEMs need at least 600 hours of burn in? I have to admit that IE8 sounds just so different after 500 hours of use compared to out of the box. I am a burn-in-believer

 

[Marcus_C]

I have to say beyond maybe a day I am not a burn in believer but it's a very nice write up. I did consider these as a replacement for my cx55's but went in another direction instead. Btw: do these and the ie series use memory wire?

 

[Prodigus Prime]

Going by the dynamics of the entry level CX6/IE6 - you can bet that IE8 would need a minimum of 600 hrs.

The IE series & CX6 have the same dynamic driver - tuned for different performance levels as claimed by Sennheiser.

And there is nothing psychological about burning-in. Its pure science of electro-mechanics.

Mechanical engineers/mechanics do the same to engines, Electrical Engineers do the same to Electric motors, the same is done for high-end thousands of dollar a metre speaker cables etc.

Any instrument, device, machine that moves or has movement in it - even if its movement of electrons or magnetic flux, need to settle in to a performance level, smoothening out the rough edges & tuning the conduction lines in coils & conductors over time to accomodate preset performance conditioning.

In IEM's - the conduction lines in coils align parallel over time, contact edges smoothen out via friction in the microscopic level, entire diaphragm surface needs to cure in to mechanical & thermal stress over time.

So if you screw up during the burn-in period or overdrive them, you can alter its final sound signature quite significantly & kill the sound too.

CX500 needs 50hrs, CX95 - 100 to 150 hrs.

Armatures too need burning-in, but probably because of cross-over losses or ear conditioning & lack of warmth, many armature IEM users don't realize it.

 

[Prodigus Prime]

The cabling does not use memory wire - but the ear-clip does.

 

[Marcus_C]

I do know that the dynamics do exhibit an initial change but I'm afraid you will never convince me that three solid weeks of pink noise through a driver 10mm in diameter will sound better than after about 2 days. As far as crossovers are concerned they are made up mainly of capacitors and inductors so about 10 seconds should suffice.

My hearing is just not good enough to hear any difference after that time that I can't convince myself is just my interpretation of the sound. Mechanics I understand, my brain, I certainly can't. What else is a forum for apart from to have differences of opinion??

Many thanks for the answer and the review

 

[Prodigus Prime]

Well Marcus, we have established the objectivity of the phenomenon of Burning-in/Running-in/Breaking-in/Curing-in/Tuning-in, now how and to what degree one perceives this phenomenon is subjective. Subjective to:

1) Ear-canal contour & differences
2) Ear - wax properties & how the distribution of ear-wax has altered the acoustic properties of the ear-canal
3) Ear-drum characteristics & differences
4) Ear-canal to External environment temperature & pressure differences, humidity, acoustic properties of the skin in the ear-canal.
5) Capability of the individual's brain to process the signal from the ear-drum
6) Imagination & Placebo effect.

So the argument can be about how one perceives the phenomenon but not question the phenomenon itself.

 

[Marcus_C]

Quote:

Originally Posted by prodigy_techus /img/forum/go_quote.gif 1) Ear-canal contour & differences 2) Ear - wax properties & how the distribution of ear-wax has altered the acoustic properties of the ear-canal 3) Ear-drum characteristics & differences 4) Ear-canal to External environment temperature & pressure differences, humidity, acoustic properties of the skin in the ear-canal. 5) Capability of the individual's brain to process the signal from the ear-drum 6) Imagination & Placebo effect.

One problem I think with these is that on the whole I find it much more likely that burn-in is percieved by the brain than the ear, being a more complex object of interpretation. If this is the case then at a time point (5) is likely to come into play and point (6) as well.

Quote:

Originally Posted by prodigy_techus /img/forum/go_quote.gif So the argument can be about how one perceives the phenomenon but not question the phenomenon itself.

This part of the argument is the one I have difficulty with. Surely burn-in should only be relevant as far as it is percieved otherwise it is irrelevant, or at least, should be. With this in mind and in view of the above should there really be strong statements that certain earphones need a certain number of hours burn-in. If, for example, a person were to read a review stating in plain terms the number of burn-in hours needed then they would understandably believe it and would be more plagued by your point (6) than otherwise natural, but is that really a perception of burn-in or just a waste of time?

After all how can any reviewer have so much confidence in there own ears that they know a difference is caused by either their ears or their brain after 600 hours when someone else with the same ears and brain cannot tell the difference at 0hrs?

 

[Prodigus Prime]

Quote:

One problem I think with these is that on the whole I find it much more likely that burn-in is percieved by the brain than the ear, being a more complex object of interpretation. If this is the case then at a time point (5) is likely to come into play and point (6) as well.

Of course yes, I am not denying that or that it had a part to play in my review - yet every other point is equally valid.



Quote:

This part of the argument is the one I have difficulty with. Surely burn-in should only be relevant as far as it is percieved otherwise it is irrelevant, or at least, should be. With this in mind and in view of the above should there really be strong statements that certain earphones need a certain number of hours burn-in. If, for example, a person were to read a review stating in plain terms the number of burn-in hours needed then they would understandably believe it and would be more plagued by your point (6) than otherwise natural, but is that really a perception of burn-in or just a waste of time?

I thought this was understood in this forum - maybe I should have explained this as well. Sound quality perception is subjective, no one can give an objective rating to a sound signature & quality level.

There is no point in wishing for an undebatable review or description of sound quality of a device or system - it will never happen. You may couple a driver with a reference microphone & compare the signal rendering to the input to decide the accuracy - but that is not an indication of what the sound makes you feel.

This is why I mentioned the player "Creative Zen", the equalizer setting & volume level - if anyone has a Zen & a CX6 then it can be a comparison of sonic tastes & burn-in after-effects.

Then again, how you burned in your CX6 & how I burned-in mine will have their own effects on the final sound signatures. When I was using CX500, it sounded slightly differently than that of the store guy's !

This is not magic, so one can only get a general idea of the *potential* of an IEM/OEM/Speaker etc reading reviews - to think that any review is exactly what they would experience is not accurate.

Quote:

After all how can any reviewer have so much confidence in there own ears that they know a difference is caused by either their ears or their brain after 600 hours when someone else with the same ears and brain cannot tell the difference at 0hrs?

No reviewer can do that - I will definitely claim no such thing. One can only describe one's experience in a review, that's the end of the purpose of a review.

If one thinks that he/she deserves a standardized output from a car, earphone, loudspeaker, bike just cos they paid huge money for it & think that for the money, the machine in contention must not be subject to a multitude of variables which can make or break their purchase - then they are plainly devoid of scientific and technical temper.

You are absolutely warranted in questioning the accuracy of my perception to that of yours - but the differences remain & can be smoothened out if we sit together & listen to the same sound from the same system & share with each other our perception of every detail of the sound.

So probably then, a basshead's *mild bass* would be his treble-head friend's *Ample bass* !!!

 

[Marcus_C]

I wasn't discussing the nature of subjectivity. Also when I said i have difficulty I wasn't stating I don't understand rather that I have difficulty believing other people's outrageous numbers when discussing burn-in. These are the main problems with what you are saying:

1) If a person bought some ie8's to use twice a day for an hourly commute to work it would be well over a year until they were at their best.
2) You can tell the difference between the same pair of earphones with several days between listens under probably different conditions (your ears change with environmental aspects as you stated).
3) Sennheiser have designed iem's to not be as good as they are capable of being.
4) I'm sure there are others but not off the top of my head.

If you can answer all of these then good for you but i remain sceptical.

As for reviews, they are, I agree, a record of your opinion. But a good review, especially on a forum, is also information from which people may make judgements about whether or not to purchase. With this in mind should it not be worth making a review as objective as possible, after all the reviewer is recomending to someone else?

All these topics have, I imagine, been covered many times on these forums, probably in the sound science forum. I tend not to visit there as I much prefer music to sound.

 

[Prodigus Prime]

Quote:

I have difficulty believing other people's outrageous numbers when discussing burn-in.

I don't *believe* in anything whatsoever. Avoid the concept altogether - you really don't have to believe anything, just get the basic idea from the pattern of any review. Its about perspective.


Quote:

1) If a person bought some ie8's to use twice a day for an hourly commute to work it would be well over a year until they were at their best.

Depends on how much of burning-in happens based on their player's amp, music characteristics & playing volume & burning-in pattern ( small gaps, long gaps, gapless, periodic pattern gaps etc ) - yes, it may be a year, depends on them, their player, their ears & their brains !


Quote:

2) You can tell the difference between the same pair of earphones with several days between listens under probably different conditions (your ears change with environmental aspects as you stated).

Ears may change with external & sound rendering with psychological changes - which is why it is better to compare IEM's/OEM's/Speakers.....simultaneously. This way you notice the differences pretty objectively, by making one reference for the other.

That's how I compared CX500 & CX95 before giving away CX500 ....and CX95 and CX6 before giving away CX95. Referencing one with the other & documenting the differences.


Quote:

3) Sennheiser have designed iem's to not be as good as they are capable of being.

Unless they run them in, in the factory with the same inputs - but then I would NEVER buy such an IEM, to me Burning-in is like customization to my taste within the performance constraints of an IEM's potential.

Unless you love customization & are really willing to put in the effort, such IEM's definitely are not worth the money - but they are to people like me.


Quote:

I'm sure there are others but not off the top of my head.

Bring them up anytime, its good to think about these things - its a humbling, yet enlightening to think about these things.



Quote:

As for reviews, they are, I agree, a record of your opinion. But a good review, especially on a forum, is also information from which people may make judgements about whether or not to purchase. With this in mind should it not be worth making a review as objective as possible, after all the reviewer is recomending to someone else?

You are right about making the review objective, how I do it is by using the same sound source & levels & comparing them with other devices.

So this way when I say "I found CX500 low on bass, med on mids & shrieking on highs, muddy detail, small soundstage, low sonic pressure"......a CX500 user can compare these levels of perceptions to those of his & then when I compare the CX95 accordingly with CX500 or CX6, the other person can form a *proportional* perspective of how the CX6 or CX95 may sound to him/her.

This is an objective as the review can get. Review a single IEM on a single source without any other reference - no way it can be an objective review........think about it !!!

 

[Nicster]

 
Thanks prodigy_techus and every one else for thorough and informative comments. I have a quick question: I have just had to return my CX6 earphones under warranty as the in-ear piece had become disconnected from the base. I thought they woudld fix with a bit of glue it but instead they sent me a new set or IE6's. I'm happy with a new set although will have to burn in again but my question is whether I've been duped with a lessor model. I'm struggling to find out the key differences between the IE6 and CX6. The Sennheiser web page comparison shows them as pretty similar with the only obvious difference being the travel adapter. Sound quality wise, does anyone know which is better or if there's any real difference? To be honest, I'm no massive audiophile so if the difference is subtle, it might be lost on me. Any thoughts? Thanks. 

 

[Prodigus Prime]

Firstly, you are quite lucky. Both the IE6 & CX6 have the same electrodynamic driver. However the key differences are that the IE6 is apparently open type and hence aimed at studio referencing, whereas the CX6 is closed configuration & aimed at providing greater passive attenuation (blocking outside noise without the use of active electronics) & slightly deeper bass response. The sound of the IE6 is going to be more enjoyable & slightly less boomier bass but you'd require more quieter surroundings than you would with the CX6.
 
Besides, the CX6 comes with a travel adapter to be used in airplanes - I don't think the IE6 comes with that but I think the IE6 comes with a bigger stereo adapter to be used with studio equipment - correct me if I am wrong.
 
It's a good thing you got a different earphone than the one you gave - it would be boring to get the same sound for another couple of years.

 

[Nicster]

Awesome, thanks for such a quick response!
Hmmm since I travel a fair bit, it's a shame to lose the greater passive attenuation - the reason I bought the CX6's in the first place. But as you said, perhaps it's time for a change of sound and I should get over the feeling of being a bit duped.
 
I still have the travel adapter for planes from the CX6 so that's good. I haven't noticed a larger stereo adapter and since I've just got them and haven't had a chance to play around too much, all I've used them with is an ipod.
 
As an aside, I was impressed with the service I got and the no questions replacement on my broken earphones. I was relieved that Sennheiser didn't come up with a million excuses as to why the two year warranty didn't apply to my problem.
 
Thanks for your info and thoughts.

 

[PocketSmiley]

Quote:

The sonically logical upgrade to CX300 would be CX95. CX500 has way too much treble that overpowers everything else.

CX95 on the other hand is supremely flat across the frequency range & IMO the flattest dynamic IEM till date.

The CX95 may seem bulky but are comfortable & are not fatiguing at all - CX300 cause bass fatigue & CX500 cause treble fatigue.

If you liked your CX300 - you will be blown away by CX95 - but you have to give it 100 to 150 hrs of burn-in period & don't give it periodic signals like pink/white noise - provide as many genres of music - bassy tracks, balanced track, treblish/bright tracks, deep vocal tracks, live - wide soundstage recordings, frequency sweeps etc etc etc during the burn in period.

 
THANK YOU for the CX95 VS CX500 comparison (I quoted your post from another thread). I'm about to take a $100 risk of ordering a CX95, a CX500, and a CXL400, which are all discontinued and are most likely fake. BUT. I have an authentic CXL400 that is unlikely to be counterfeited due to its delicate construction and relatively low MSRP, so my chances aren't that bad. The original Sennheiser CX series means so much to me much more so now that after I have compared them to many others they still stand above the rest. I only regret not getting the CX500 from an authorized seller when I had the chance--I was too satisfied with the CX400 that I thought the little difference in sound quality was not worth the price. Now that I'm convinced the CX400 is the best IEM for me, getting the higher model in the original CX hierarchy is a reasonable desperate step. (I differentiate between the old and new CX lines because, aside from numbering the new ones more randomly, Sennheiser apparently released entirely different successors to the original CX300 and CX400.)