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Philips Fidelio X1 | Comparison & Review

A Review On: Philips Fidelio X1

Philips Fidelio X1

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Philips Fidelio X1


Philips Fidelio X1 | Review & Comparison




Quick Summary

(As compared to AKG's K702 Anniversary and Q701)



  • X1:  Warm and smooth but with a slight "U" shape, a little more of a "fun" signature, bigger bass w/deeper extension, mids less prominent and a bit more neutral sounding, slightly more treble sparkle.  Soundstage size is pretty similar to the Anniversaries, but with smaller instruments and a little more distant presentation.  As a result, inside the soundstage there is a little more spaciousness and room and slightly better imaging.


  • K702 Anniversary:  Also warm and smooth but with a flatter more balanced signature and more natural timbre, less bass, mids fuller and lusher, treble a little warmer/smoother.  Soundstage size is pretty similar to the X1, but with larger instruments and a bit more intimate presentation. 


  • Q701:  Thinner, lighter, drier, faster, more mids (and upper mid), and airier.  Less body and weight to mids and bass.  The soundstage is a bit more distant sounding and instruments float more.   




Philips Fidelio X1     Philips Fidelio X1     Philips Fidelio X1




The X1’s packaging is pretty nice and looks fairly classy and clean, apart from a somewhat obnoxious white “Philips” badge.  The box has a nice smooth finish and is made of thick and sturdy cardboard.  There are two pieces to the box and the top part pulls apart like a lid.  One thing I like about the X1's box is that it can double as a case for the headphones.  I store my X1s back in the box when not in use.  Inside the bottom portion of the box, the headphones and cable are fitted into a velvety-covered molded plastic piece.  If you lift that molded piece out you will reveal the rest of the cable as well as a nice little paperback booklet detailing the headphone (Philips is clearly proud of this can).  The headphone also comes with a gold plated 1/4" to 1/8" adapter and a little plastic "cable management" piece (not pictured), which is meant for looping your cable around to take up some of the slack.






Philips Fidelio X1     Philips Fidelio X1     Philips Fidelio X1




I was attracted to the X1s as soon as I first saw pictures of them as they had all the physical traits I prefer in a headphone:  open design, large spacious ear cups, velour pads, detachable cable, and self-adjusting-headband.  They were also one of the best looking headphones I'd seen.  Seeing them in person now, I can confirm that they're physically beautiful.  The colors, materials, and finish all look and feel great.  These are a very classy headphone (apart from a small and unnecessary "High Definition" branding on one of the earcups, no doubt influenced by the Philips HDTV division - luckily it's hardly noticeable).  They feel pretty solid and tightly constructed.  There's very little play in the parts.  Even though the build seems good, I would still be careful with the X1s and wouldn't throw them around - because they are so tightly constructed it almost feels like something will break if impacted due to a lack of play in the parts.  IMO the X1s are a headphone meant to be used at home and babied.  Philips seems to have been thinking the same thing as the box even says "indoor headphone" on it!  tongue.gif


The X1 weighs a little more than the AKGs, but they're not bad at all (the AKGs are a VERY light headphone after all).  I think the actual weights are 362 g for the X1 and 235 g for the AKG.  Philips refers to the X1s headband as a "self-adjustable airy hammock with 3D mesh."  It's a self-adjusting headband design similar to the one AKG uses, and it works well.  One thing that surprised me was the amount (or lack thereof) of headband extension.  There isn't a ton of room, and I can potentially see it being a problem for larger heads.  For my smaller head, it's pretty much a perfect fit.  If you do have a larger head though, there is still hope as the outer bars are bendable.  You should be able to free up some extra room by repositioning them as needed.

Here is a size comparison picture between the X1s and AKGs:

Size Comparison (Click to show)


I've heard bad things about the stock cable, which is a shame because it's quite handsome.  It's black, 9 feet long, and is of the braided variety.  It terminates into an attractive 1/4" plug (a 1/8" adapter is included).  The microphonics on the cable are surprisingly loud, although I don't care, as I would never walk around outside with an X1.  People say you should replace the stock cable in order to improve the damping factor a little (due to high resistance in the stock cable).  I measured the stock cable's resistance and got 1.8 ohms, which is on the high side.  It's easy to replace the cable as it simply connects via a 3.5mm jack on the left ear cup (speaking of which, I'd recommended taking extra care not to accidentally damage that earcup jack).  If you do decide to replace the cable, I recommend NOT going crazy and instead just getting an inexpensive one.  The Monoprice "mobile" 3.5mm cables are a good option.  I've measured the 6 foot version to have a low 0.4 ohm resistance and it's attractive, comes in multiple sizes, and is dirt cheap.  The Mediabridge 3.5mm cables are basically the same just in a different color.  You also shouldn't expect that much to change when replacing the cable.  We're talking about a VERY small difference in the sound here.   These are CABLES after all!  I just don't want people to get out of hand and start chasing different cables, suddenly hearing all kinds of subtle placebo-ish differences in their X1.  My advice is to just get a solid $5-10 cable to avoid the stock cable's resistance issues, then forget about cables and just use the damn headphone.


Apart from the few issues mentioned, I think Philips did a great job designing the X1.





Philips Fidelio X1     Philips Fidelio X1     Philips Fidelio X1




I find the X1s to be incredibly comfortable - one of the comfiest I've used.   The headband has an ample amount of padding and is quite wide with a lot of surface area to distribute the weight, so the headphones feel light on the head.  The ear pads are also amply padded, with soft velour wrapped memory foam, and the ear cups are quite deep - deeper than the Anniversaries (although slightly smaller in diameter).  They're not quite as deep as the thickest part of the Q701 pad, but almost - and it's the same thickness around the entire pad.  For big-eared head-fiers (myself included) these are one of the deeper earcups out there.  The earpad openings are oval shaped, and that oval is tilted back to line up with the shape of your ears.  The pads themselves are not angled but the drivers are.   One small thing I've noticed is that strong bass can cause the cloth material covering the drivers to vibrate a little, and if the tips of your ears happen to touch this cloth it can occasionally cause a minor tickling sensation during that type of bass.  Most of the time it's not really noticeable, but I feel I should still point it out.  Interestingly, the cups don't really pivot side to side, however it seems to be a non-issue in terms of their fit.  I don't feel any unusual or excessive clamping pressure with the X1s.

The velour pad material is a different type than what AKGs uses.  It's sort of shiny looking, but it's soft and feels nice.  There doesn't seem to be any itchiness, a problem I've mainly had with Audio Techinica pads.  The only bad thing about the earpads is that apparently they're GLUED ON (*face palm*) and are NOT designed to be replaced.  On a headphone this expensive, this is a pretty bad oversight.  I don't know if Philips (or I guess I should say "Funai" now) listens to feedback, but….replaceable pads please.   I can't tell you how much I adore AKGs removable bayonet lock pad system.  My only two complaints with the design are the fixed pads and the less-than-great stock cable.  The latter is much less of an issue of course, since you can just use your own cable.  But the fixed pads should to be addressed IMO.

I find the X1s to be a little more comfortable than the Anniversaries, mainly due to the deeper earcups and more generous headband padding.  I also prefer the Q701 earpads to the Anniversaries, again due to their greater depth.  All three headphones are very comfortable though and are useable for multi-hour sessions.






Philips Fidelio X1     Philips Fidelio X1




Before I listened to the X1s, there were three potential sonic deal breakers I was worried about.  They were:  How bright will the treble be?  How recessed will the mids be? and Will the bass overpower everything?  After getting them I was pleased to hear that none of these turned out be an issue.

The X1s sound fairly warm and smooth with big bass and just a hint of treble sparkle (but still smooth sounding).  The mids are thankfully present and not recessed, and are slightly warmer than neutral.  Even though the X1s are warm sounding, they still have a mild "U" shaped response that pushes them a little more towards that fun home-theatery type of signature.  They are still pretty balanced sounding though, with good genre bandwidth.  The soundstage is on the large side and is spacious sounding with good separation and imaging.  Considering the warmth of the X1, their overall speed is pretty good.  They also have a pretty good texture to their sound.  The X1s are a bit less dry sounding than most open headphones.  It seems like the X1's have a little better room ambience, meaning you can hear the reverb from the recording space a little better, while the Anniversaries are a little drier in this regard.  With the Anniversaries you can hear more low level noises, like chairs squeaking (although this is partly related to the more forward mids).  The X1s are pretty easy to drive, and like most open headphones they leak quite a bit of sound.

The Anniversaries in comparison to the X1 are flatter and more balanced sounding, with fuller lusher mids.  The Anniversaries treble is slightly warmer, and combined with their lesser bass quantity they end up sounding slightly "n" shaped coming from the X1s.  The soundstage size is similar between the two, although the Anniversaries instruments can sound a little larger and more intimate, while the X1s smaller more distant instruments can make their soundstage sound a little roomier.  The Anniversaries timbre usually sounds more realistic and natural, although the X1s are still a bit decent in this regard - better than some other mid-fi cans I've heard.  The Anniversaries are also more refined and "audiophile" in sound, and the X1s forgo some of that.

The Q701 is definitely a lighter, brighter, drier, and faster sounding can then the X1.  There is greater air and emphasis on upper mids and highs.  The bass is light next to the X1.  The soundstage sounds a bit farther reaching.



The bass on the X1s is big, fun, and enjoyable.  Its quantity and extension are both surprising for a headphone this open.  It can be a little loose and one-notish at times, the speed and texture aren't perfect, and the bass loses a little quality and smoothness as it goes into the deepest frequencies, but I partly feel these are somewhat acceptable concessions for the X1 to make.  While some of the X1's bass technicalities may not be the best, whatever compromises it makes to achieve it's "fun" sound seem to be worth it, as once you're listening and enjoying it the minor details often become irrelevant.


The X1 actually has a bass hump around 65-70 Hz, which is pretty deep bass. That's into sub-bass territory, and it makes for a fun addition with movies and games.  The X1s still aren't quite a "bass head" can - they sound too balanced for that.  They're able to manage good genre bandwidth, with enough bass to inject fun into electronic genres while still being able to pull off classical and jazz without the bass overwhelming.  While the X1s bass is a bit accentuated, it thankfully transitions nicely into the mids.  Headphones like the DT990 have a problem where they have lot of mid bass impact but don't have much midrange to transition into.  As a result their bass ends up sounding a little weird and isolated from the rest of the frequencies (IMO).   The X1's bass is more smoothly connected to the mids and sounds more natural and balanced as a result.  The Anniversary takes this a step further, with the bass and mids further blending into each other. 


Compared to the Anniversaries, the X1's bass has greater quantity in both mid and sub-bass frequencies.  There is greater body and impact on the X1.  The X1 also has a lengthier decay, a quality more often found in closed headphones.  The Anniversaries bass speed is a little better, and they keep a little better quality into the low sub bass, sounding a bit smoother on the lowest frequencies.  The Anniversaries bass is flatter sounding and is more modest and balanced with the rest of the signature.  The X1's bass forgoes that for more fun, and is capable of underlining the whole track with a layer of fun that is more difficult for the Anniversary to pull off. 


What surprises me about the X1's big bass is that it's all happening inside a pretty large and open soundstage.  This is an impressive feat considering that it's uncommon for a headphone to have both of these traits simultaneously.  Usually a headphone will focus attention on one or the other, but the X1 ambitiously goes after both of them, and the end result is a pretty cool combination.


To Quote Happy Bullets,

"It is almost like they take the immersion and fun that some closed cans offer and perfectly mix that into an open can."


Overall I feel that if you can look past its imperfect technicalities, the bass on the X1 is a lot of fun.




I've tried a couple of the popular "fun" headphones, and they often seem to overly color or neglect the mids.  I like the X1s because they seem to do a good job at sidestepping this problem, presenting a competent an even-sounding mid-range in-stride with the rest of the signature.  

The X1 mids are present and not deficient, but they're not a particular focus either - not the same way as on the Anniversaries.  The Anniversaries mids are definitely one of its highlights, and it has a midrange that's not only more forward and engaging but also more lush and organic sounding.  Sometimes the mids on the Anniversaries can really reach out and grab hold of you, whereas the mids on the X1 are more content to just get through the song.  The Anniversaries mids are a little warmer while the X1's are a little more neutral sounding, but the X1s mids still have a little smoothness to them.

The Anniversaries mid-range is thicker, fuller, and more intimate - the mids on the X1 can sometimes be a bit distant sounding in comparison.   While I normally don't strive for an intimate sound, I can hear the appeal it can have - sometimes when listening to music on the X1s I want to turn the volume up louder to bring back some of that intimacy.  On the other hand, sometimes I don't want that intimacy, and during these times I prefer the X1s approach more.  Some examples are gaming, movies, and TV - all areas where I tend to prefer a more distant presentation.  The way the X1 presents its mids seems to allow it to free up a little more space and room inside the soundstage, which seems to benefit all the just-mentioned examples.  If you are specifically looking for an intimate mid-centric headphone, you may want to think twice about getting the X1.  You should probably look into the HD650 or Anniversaries instead.  There are plenty of mid-rich as well as mid-recessed headphone options out there, but there is a fine line in the middle of the two and I think the X1 falls more closely into this area.

The Q701s mids are also nice, with good clarity.  However they can sometimes be too light sounding, lacking in body and weight next to the warmer X1 and Anniversary.  Another issue with the Q701 is that some of the upper mids are occasionally too forward and can become a bit hard, strident, and glaring.  This is definitely less of a problem on the Anniversaries, but they're still not immune to it.  The X1 is pretty much in the clear though, and if you're listening to a recording that has overly forward mids/uppermids in the mix, the X1 can sound less fatiguing. 
Overall I'm pretty happy with the mids on the X1 and they fit naturally in with the rest of its sound.




The X1 has an interesting and slightly unusual treble.  They have a hint of treble sparkle, but it's probably less than you're expecting - these are still a warm and smooth sounding headphone.  While there is that hint of sparkle and clarity the X1s also roll off the uppermost treble fairly quickly.  This prevents sibilance and keeps the sound smooth at the cost of covering up some highest frequency details and hampering the air some.  The treble ultimately ends up sounding sort of smooth and sparkly at the same time.  Sometimes the X1s treble can sound a tad artificial and unrefined, but I consider this somewhat normal for this price range - in other words, just a little reminder that this is still a "mid-fi" dynamic can.  The AKGs do have a bit more refinement in their treble though.


The treble on the Anniversaries is slightly smoother than the X1, but the Anniversary also draws more brightness from its stronger upper mids.  As a result the X1 usually doesn't sound that much "brighter" in a comparison.  The Anniversary can even sound brighter on certain tracks depending on what's going on.  Also affecting the perception of brightness is the lesser bass quantity on the Anniversaries, which makes them sound flatter, while the stronger bass on the X1 adds more weight and warmth to the sound. 


Neither headphones treble or brightness sounds offensive to me.  Sibilance isn't a problem on either.


While the amount of air is close, I think X1 has just slightly more.  Although the Anniversaries have slightly warmer treble, I think their treble is also a bit more linear, rolling of more slowly as it extends into the highest frequencies - helping it keep similar air to the X1.   Q701 still clearly has more air then either of them and they are definitely brighter sounding headphone than the X1s - no doubt aided by their more prominent upper mid presence.


The X1s are NOT comparable to the DT990 and HE400 in terms of treble.  The DT990s will still sound sizzling hot next to the X1s.  The much better balanced HE400s are still a couple notches up from the X1 in treble.


I personally wouldn't mind slightly more treble and air from the X1 (same way I feel about the Anniversaries), but I also think it's pretty good as is and walks a safe middle ground.





For me, this is a VERY important aspect of sound.  In fact, it was pretty much THE determining factor on whether or not I would keep the X1s - I'm absolutely a soundstage whore, and I could care less about the rest of the X1s sound signature if it did it all with a small and claustrophobic soundstage.  Luckily the X1s soundstage and imaging were a pleasant surprise.  Both were better than I was expecting and they sealed the deal for me.

The soundstage is large and similar in size to the Anniversaries, although less intimate sounding.   This is sort of similar to the often used "closer to the stage Vs. a few rows back" description, but I think that phrasing is a little cliché and over generalized for describing a headphone's presentation.  Soundstage width is similar between the two.  The X1 may have a little advantage in depth - in part due to their less intimate nature.  Height is also fairly similar between the two, although the AKGs may have a slight advantage due to their larger sounding instruments.

The X1's imaging is quite good.  I was expecting the X1s imaging to be a bit diffuse and hazy, but it's surprisingly focused and sharp.  I actually find the X1's imaging to be a bit better than on the Anniversaries.  The X1's secret to pulling this off is its smaller less intimate sounding instruments.  They tend to make the X1's soundstage come across as being a bit more spacious and roomy then the Anniversaries - not necessarily larger, but roomier.   This is similar to the reason why the Q701's soundstage has an advantage over the Anniversary - but the X1s sound a lot more fun while doing it.  The different presentation seems to sharpen the imaging and improve the separation a little.  The extra roominess is more noticeable and appreciated when gaming then it is with stereo music.  In contrast to the X1s, the Anniversaries instruments are larger and more intimate sounding, and as a result things can occasionally sound more diffuse and crowded inside the soundstage.  As the size of the instruments increases, it often becomes more of a struggle for the headphone to keep an impression of soundstage size, space, and distance.  The Anniversaries fuller mids aren't helping anything either.  The Anniversaries larger more intimate sounding instruments can be a cool effect, and are often appreciated for music, but for gaming and movies the X1s seem to benefit a little more from their type of presentation.    

The Q701's soundstage still sounds a little larger and capable of placing things farther out, although a fair amount of that comes as a result of their lighter airier signature.  The instruments of course will "float" more on the Q701s, with there being less weight and low end to ground them.  


Overall I feel the X1's soundstage and imaging are both excellent, and are one of the X1's highlights.

More soundstage talk in the gaming section…



The X1s are probably the best overall gaming headphone I've personally heard.  I say this because they have the highest combination of "competitive" and "fun" abilities that I've heard in a single headphone. 

During my first initial listening session with the X1, I could tell the signature coming from them would be great for gaming, and they didn't disappoint.  The combination of a slightly fun-tilted signature with immersive bass, open soundstage, and clear imaging makes them almost specialized for gaming and movies.  The X1s work really well with Dolby Headphone, projecting a large and coherent soundstage without any abnormal jumps between sounds - objects pan smoothly around the soundstage and there's a good amount of spaciousness to be heard, which is surprising considering the warmth of the X1.

Earlier I mentioned that the X1s mids sometimes sound more distant when compared to the Anniversaries, but when gaming I want to hear space and distance - and the X1's can do this a bit better than the Anniversaries while still keeping a weighty sound.  The Anniversaries larger instruments and greater intimacy can sometimes throw you off on distance, occasionally making distant sounds seem a little bit closer than they do on the X1.

I prefer the X1s to the Anniversaries for fun and immersive gaming because they combine a more fun tilted signature along with a slightly roomier soundstage and slightly sharper imaging.  All three of those things improve the immersion for me.  With the Anniversaires, the full mids, natural timbre, refined sound, and larger sounding instruments all give it nice immersion as well.  But things like refinement and timbre are bit less important for gaming than they are for music, and I think the soundstage whore in me caves a bit to the X1's roomier soundstage and immersive bass.
As far as competitive gaming goes, if the X1s lose any points it's not because of their soundstage or imaging.  They are warm with a fun signature though, and the bass can be a problem at times - covering up subtle details in the mids (which are already more laid-back then the Anniversaries mids).  Running the X1s through a bass reducing EQ would probably help some for competitive gaming.  The Anniversaries are flatter and more balanced sounding, with more reserved bass and more obviously forward mids, which is an area where a lot of the competitive details lie.  The X1 do gain more soundstage points over the Anniversaries for sounding a little more spacious with sharper imaging - the Anniversaries soundstage sounds a tad more crowded and diffuse.  All in all, it's kind of impossible for headphones like the X1 to truly excel at competitive gaming, since the best headphones for that will always be the ones that focus on presenting just those fine details in the mids and highs (footsteps/reloading/etc.) while keeping the bass reserved and out of the way.  Still, I think the X1s do a damn good job of pulling off the best competitive ability that they can while still managing the fun signature that they do, so I don't fault them for any shortcomings in that area.

Overall I would rate the X1s competitive ability somewhat similarly to the Anniversaries.  When listening for positional cues and details with both of them, I hear a small soundstage/imaging advantage for the X1 but a signature advantage for the Anniversary.  I feel the two differences almost counterbalance each other, but the ultimate deciding factor may come down to the bass.  I won't quibble over the fine details though, as I usually reserve my competitive gaming for the Q701s.  They still hold a small competitive advantage over both the Anniversary and X1 due to their faster, lighter, clearer signature coupled with their open soundstage.  With my pair, I can also control their level of bass with a flick of a switch (literally).  For immersive gaming, while the Q701's open airy soundstage does gives them their own brand of immersion, they are lacking in weight and body next to the Anniversaries and X1s which ultimately puts them at a disadvantage.  Bass boosting them helps, but the mids will still lack some weight and body and they will still be on the dry side.  In my opinion, the X1s hold an edge over both AKGs in terms of fun factor and immersion.


I should mention for people who already own the Anniversaries...do keep in mind that they're already one of the best overall gaming headphone options out there.  While they now have some healthy competition in the X1, it's not like it's "on another level."  It's just a little different flavor of sound.  If the X1's sonic traits and signature described in this review sound appealing to you, then by all means check them out - but if you're going to stick with the Anniversary/Q701, they are also one of the best in this range. 

Overall the X1s are my top recommendation for all-around gaming headphone.  The Anniversaries are a very close second.  You may want to choose accordingly though, based on whether you would prefer a fun tilt or a balanced tilt.  The X1s are also a strong recommendation for movies and TV, which benefit from the same sonic traits that contribute to a more immersive gaming experience.





The X1s are solid recommendation in this price bracket.  I feel the X1s make a nice compliment to a flatter and more traditional "audiophile" headphone, but they're also balanced enough that they make for a very good all-purpose headphone on their own, with a special talent for games and movies.  They're also very comfortable, easy to drive, and are downright gorgeous looking.


As for the inevitable question of "which headphone is better" between the Anniversary and X1?  I really don't think you can generalize that one is "better" than the other, because they both go in two different directions (I feel that statement holds true for many other headphones as well).


To quote Mad Lust Envy:

"That's how I feel as well. Two different kinds of awesome.

The Annie is more balanced, the X1 is more fun. Both have their place, and both are special to me.

It's really apples vs oranges."


I can't fault the Anniversaries for being more balanced and I can't fault the X1s for being more fun.  One single headphone can't simultaneously be both flat and balanced AND bassy and fun.

That's why they compliment each other....and that's why I've kept them both.



My closing thoughts on the X1:

The X1 is an interesting headphone.  It's not the most refined and "audiophile" of headphones, and if you break down its sound into its individual elements and examine their technicalities, some of them may not come across as particularly impressive.  But what makes the X1 special is not its individual technicalities.  The X1 strives to be a Jack of all trades, and I don't mean that in a bad way.  It's a headphone that ambitiously tries to combine some of the best traits from other headphones together - and for the most part, it succeeds.  It's able to pull off a spacious sounding soundstage and a warm fun bass-infused signature simultaneously - all while sounding surprisingly balanced overall. In short, the X1 is a headphone where the whole is greater than the sum of its parts, and if you're willing to take a step back and accept the small compromises it makes along the way, you're in for one of the more fun and enjoyable listening experiences this price bracket has to offer.


IMO.  wink.gif


Kudos on the great review! I've actually been eyeing these for a little while now. I was most curious about the bass capabilities for being an open can. Not a basshead, but I do enjoy a fair amount for EDM. These just might be for me :)
Thanks. I'm ignoring this for awhile because I don't want to get interested in any more headphones!
Non removable pads on a headphone this expensive is a total fail. I would never buy a headphone unless I could remove it's pads.
I hope Philips actually listens to feedback and changes this.
Great review!  Well written and concise.  Kudos.
Nice review, the Philips models are better and better.. Wake up AKG!!!
I have had these since its launch. For large heads like mine, I've bent the metal headband to be more cone-shaped (Tyll mentioned that in Innerfidelity), as well as cut the elastic that threads through the lower cloth headband. I've also found that the ear pads can be pulled off and there's no real need to glue them back. They are held with 5 plastic studs that can just snap on and off. Then you can experiment with different ear pads - amongst those I've tried are Beyer velours, LCD, Mad Dogs angled pads, AKG K550. These pads may not look as elegant but the operative word is "experiment". Comments and pictures have been posted on the impressions thread many times in the past.
Great looking photos and well done review. Should be a great reference to potential purchasers.
Hello again! I just pulled the trigger on one, and your review was in part what made me decide to go with these cans.
Hnnngh. This review is not helping me save money...
The links to Amazon are for the L1, not the X1. The X1 is closer to $300, not $185.
I keep seeing people refer to sub-bass as 60-70 Hz. I think sub-bass is 40 Hz and below. 60-70 Hz is lower bass.
This makes me want the X1's even more. my wallet is itching. 
dpump : "I keep seeing people refer to sub-bass as 60-70 Hz. I think sub-bass is 40 Hz and below. 60-70 Hz is lower bass."
Right on, the lower end of the low-bass is 40 Hz. Below around 40 Hz the tones are breaking up, they lose their continuity [to human hearing].  40 down to 20 Hz is sub-bass.
And hear (jk) I thought all headphones were supposed to be "fun". Fun, fun, fun, fun, and fun.
This needs to stop being on the front page of Head Fi. It's headphone porn like no other.
It's disappointing to read that the pads are not changeable, not sure how that could have been overlooked on the design. Pads never last forever, with the fact you can't change them it basically adds a shelf life to these headphones and almost makes them impossible to justify spending money on. Too bad, because other then that they look like great headphones. The sound signature sounds very appealing and the design looks really nice to me.
A really thorough review!
me likes, thanks man!
Excellent review. Thank you so much for elaborating on the ear cup space. I owned both the K702 Annies and Q701s, and the drivers on the Annies DID touch my left ear and cause some irritation, but not the case with the Q701s. The angled drivers make all the difference. Something I wish the Senn HD650s had since they make my ears hot from the driver covers touching them. I also agree with you on the DT990 Pro. While the mid bass and lower bass are fun, the upper bass is a little too lean and makes the bass rather removed sounding from the mid range, and tends to sound somewhat droning and cold. Of course a tube amp DOES help some. An upper bass to midrange transition is crucial to a groovy and musical headphone, something the AKG K240 does extremely well, if it were not for that painful sibilance spike. 
I use an Inakustic Star 1.5M cable ( measured at 0.7 Ohm resistance) and the sound becomes much more neutral, sounding like a slightly warm DT880, which is perfect for me.
One should keep in mind that X1 is 250-300$ while 702 anniversary is between 450-650$. Huge difference and still competes with the 400$+ h/phones. What a huge success from philips before retiring from producing hi-fi equipment.
Awesome review btw. Thank you.
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