[MacedonianHero]

  I think anyone considering on spending in the sub $400 range should consider auditioning the PSB's.
 
I'm far from a bass hungry listener so I do find the M4u4 pleasing in "deep enough" bass reproduction. Overall the musical presentation is very good even if you do not consider the cost of the headphones w/ replaceable cables.
 
For an entertaining audition I'd urge anyone to test a B&O Beoplay h3. A cheaper earphone with thinner guage non removable cables. The "air" for a semi open headphone seemed noticeably larger in soundstage with a much more cleaner presentation. I actually hoped the PSB had that identical sound performance. The catch is I'm wanting robust earphone with sound isolation with removable cables.  The H3 has a rich presentation with neutral bass which I'm after.
 
The M4u4 is a solid performer that appears to be built to last. Infact I deliberately used my iPhone 6 plus as a source using Tidal stream. This is my intent of these earphones for portable leisure listening.
 
I also compared the Shure SE425 and found them to be "dull" with a lack of dynamics. The clarity seemed to be lacking while I listened to tracks of jazz vocals from Melody Gardot. I was not impressed with the sound of the SE425.
 
In the same "testing" I tried a pair of RHA T20i. A darker heavier sound but for a "Bass Head" they'd appreciate the added eardrum damaging effects these earphones can provide. Clarity was much better than the SE425. The SQ seemed to be almost on par with the M4u4 earphones in the clarity/neutral department but a tad darker with much deeper bass. This is not my criteria I was looking for so the audition of the earphones ended 2/3 into listening to Diana Krall's "California dreamin'"
 
As anything goes for headphones/earphones it all comes down to personal taste. If it wasn't for the delicate design of the B&O h3 non removable cables I would purchase those compact beautifully fitting earphones for my application. The PSB's are on my shortlist that is cheap enough to grab for giggles but SQ is a downgrade from the B&O H3. For such a portable "transducer" I find the PSB m4u4 much more pleasing than most of the portable head gear like the Senn Momentum 2, Aedle VK-1, Audio Technica ath-m70x etc. Going from memory (frightening to say...) the Denon AH-MM400 is the only portable headphone gear I'm also considering for "portable" use. The laws of diminishing returns is present in anything we buy. The PSB M4u4 is a sweet spot IMO for sub 400 buck price point and sonics.

 
Great impressions...I would however expand your price range to the $500ish region...I prefer these to the W40 & SE535. They are that darn good to my ears!

 

[AlanU]

   
Ah, cool, thanks for the follow up.  I agree about treble - I'm quite sensitive to it too, so a non-fatiguing signature would be what I'm ideally looking for.  I've never understood those who love treble - seems to me that real music in the real world doesn't or shouldn't tire you out or do your head in, so I don't expect my earphones to do that either.
 
If I get the M4s, I'll report back on impressions.

After analyzing my requirements I decided to just buy the M4U 4 on my way home from work.  In the crazy world of earphones/headphones I understand that there is never an ideal and diminishing returns after a certain point of $$ outlay. 
 
My simple checklist was to have a closed non vented earphone so that low volumes can be played without combating external noise. This allows comfortable low volume levels. Over ear hanging of the cable prevents noise from transferring to the earphones. Removable cables is a good bonus. The PSB is semi bulky but definitely tolerable.
 
I wont claim outstanding ground breaking SQ from these earphones. However the flatter freq response in the upper high freq range suites my ears. I appreciate a tiny bit of sparkle but over extended periods I did not want a bright earphone. At this price point I really think they have great value in sound quality and build.
 
Seems there's a range of earphones in the 300-500 price range. The decision I made was easy since I was not wanting accentuated BASS enhanced earphones or extremely bright earphones. 
 
I listened to a tiny set of Klipsch X11i and they didn't seem to do much for my ears. I swear I thought I was wearing a inexpensive pair of my $75 Klipsch earphones I bought 3yrs ago for recording level purposes for my HD Camcorder. 
 
Listening to Julia fordham her voice seemed very natural. I feel the flatter treble response provides very good clarity but not the higher degree compared to other earphones.
 
I've been listening to these M4U4's for a while after my purchase and they seem comfortable enough and no experience of fatigue.
 
Toom, in your local area these earphones is a substantial chunk of money.  I'm pleased with my purchase. I doubt I'd get buyers remorse since these earphones sound substantially better than the Shure SE425. 
 
I'll continue to listen to other earphones for giggles. For the $$ I am quite pleased with the SQ of my latest acquisition
 
 

 

[AlanU]

   
Great impressions...I would however expand your price range to the $500ish region...I prefer these to the W40 & SE535. They are that darn good to my ears!

I'll take a listen to the SE535. I dont think I tried that set yet....

 

[Toom]

I'd be interested in more comparison with the SE535, as that's been on my radar for a while now....

 

[AlanU]

I'd be interested in more comparison with the SE535, as that's been on my radar for a while now....

 
I was looking at those earphones but didn't audition.  I just wasn't enthusiastic in testing "shure" products after getting a very forgettable audition of the low clarity sound I heard with the SE425. Just thinking about it I wasn't logical... I should of tested the SE535.
 
The cost difference of the PSB m4u4 to the SE535 is aprox $330 CDN extra. Now that I'm not doing A/B testing and "in home" I'm finding the M4U4 "clear enough" in the clarity department. The PSB earphones is not bright hyper detailed or fatiguing. 
 
Discussing the earphone selection at the headphone shop it seems in order to jump into a different league in higher SQ from the $200-600 "crowd"  many hardcore enthusiasts jump to the $1000+ mark $$$ for earphones. The same logic applies to many flagship higher end speakers in the audio world. 
 
Every earphone has a certain signature sound that is "different". Seems the top tier flagship earphones are a big step in SQ. The 200-600 dollar crowd seems "different". Such a subjective personal decision
 
I'm still going to test more earphones for fun Since I'm not a Basshead the earphone selection diminishes. Depending on how the manufacturer wants to target buyers they will design the earphone to have specific characteristics which can be voiced in many different ways. My particular case neutral/warmish and not "bright" is what I find the PSB's to be. Of coarse this discussion should also include the source/amp used. Listening to the Astell/kern Jr. the music presentation became cleaner in clarity and to my ears marginally cooler and leaner and I got the same impression as I tested the PSB with the concero HP dac/headphone amp.
 
Toom this fun enjoyable hobby is spendy. My justification in the PSB was going for a non fatiguing enjoyable sound. Spending more for a 600 dollar set didn't change the game to a new higher level of SQ. Diminishing returns when you hit the higher end earphones in the 600 dollar range. After discussing with a seller in the headphone world seems the sweet spot in great earphones is in the 200-600 buck range and then there's the market for a jump in $1000-1200 in the high end arena. For "on the go" listening i personally cannot justify the cost of top tier $1000+ earphones. For that price I'll add higher end full size headphones for my headphone rig at my work desk at home. 

 

[Toom]

Well, I've pulled the trigger on the M4s, so should have them tomorrow - will report back.

 

[Kundi]

  Well, I've pulled the trigger on the M4s, so should have them tomorrow - will report back.

Where did you buy them from?

 

[Toom]

  Where did you buy them from?

 
Advanced MP3 Players, here in UK.

 

[Toom]

  I listened to the review pair of M4U 4s today all morning at work and they are a home run! Paul Barton and the team at PSB really hit it out of the park with these IEMs!
 
Simply one of the most neutral and balanced presentations I've come across in IEMs and only surpassed in this respect by the JH Audio Layla's to my ears.  If you love the sound of the full sized M4U 2s but want a smaller form factor, you need to hear these IEMs!
 
More to come...

 
So, my M4 U4s arrived a short while ago, so this is just very very early impressions, but with that caveat I will say that you are absolutely spot on with this comment.  The comply tips don't do it for me - the fit and isolation is supreme, of course, but the sound is just too dark and thick with them.  So I've swapped to the large silicones and oh my word do these things sound lifelike!  So natural, so unforced, so immersive.  Bass is not overpowering like others have said, not at all.  And neither is it lacking, as that Soundstageexperience reviewer commented. Nice package and build quality too.  Smaller earpieces than I was imagining them to be.
 
Of the hybrids I've tried - Trinity Delta and Fidue A73 - these are undoubtedly superior. By some margin. Of course, they are twice the price, but still....
 
Like I said, early days still of course, but I think these could be champions.

 

[Toom]

Just to add, I've swapped out the supplied silicone tips for some pretty generic ones and they are producing great results:
 

 
The supplied silicones are longer and more narrow and I haven't seen them before, so I wonder if they are common to other brand IEMs? They don't fit my ears as well as these rounder ones.

 

[AlanU]

   
So, my M4 U4s arrived a short while ago, so this is just very very early impressions, but with that caveat I will say that you are absolutely spot on with this comment.  The comply tips don't do it for me - the fit and isolation is supreme, of course, but the sound is just too dark and thick with them.  So I've swapped to the large silicones and oh my word do these things sound lifelike!  So natural, so unforced, so immersive.  Bass is not overpowering like others have said, not at all.  And neither is it lacking, as that Soundstageexperience reviewer commented. Nice package and build quality too.  Smaller earpieces than I was imagining them to be.
 
Of the hybrids I've tried - Trinity Delta and Fidue A73 - these are undoubtedly superior. By some margin. Of course, they are twice the price, but still....
 
Like I said, early days still of course, but I think these could be champions.

 Sounds like your pleased with the sound signature.
 
What is quite interesting is that since these IEM's are so easy to drive I'm actually enjoying them alot with my iPhone6 plus using Tidal stream (offline when on the go).
 
Testing these earphones with my Burson Virtuoso I'm finding that the clarity has improved in a small way. The smartphone that is already with me 99.99% of the time has performed surprisingly well. I also tested these earphones with my Samsung Note 4 and I'll have to admit my iPhone6 plus has substantially better SQ  by a large margin.
 
Without considering price these earphones do have a very likable sound signature that is non fatiguing and provides "just enough details" to enjoy the music rather than analysing it with an over abundance of micro detail. There's certainly better out there but this is where $$$ and diminishing returns comes into play. When the Cost factor $$$ is in your head as you listen I think these PSB's are top of the game for the kind of SQ you get.
 
After auditioning the Klipsch X11i and slightly more expensive Shure 425's I was so underwhelmed it those two sound signatures. The free Apple earbuds that comes with the Iphone6 plus has similar "meh" sound quality. Listening to the PSB's the jump in SQ is very noticeable.
 
Now that I've listened to the PSB's extensively with all kinds of genre I do question if the Shure 535 (costs aprox $370 more than PSB) and if the price is worth the extra "ballpark" $400 dollars.
 
In my particular case IEM's are a nice to have...... for the price point I'm quite impressed and happy with the setup I now have. Never in my life I thought an iPhone could provide such a decent sound quality. Backgrounds could be blacker but for thousands of albums on tap "offline" I cannot complain. 

 

[Kundi]

   Sounds like your pleased with the sound signature.
 
What is quite interesting is that since these IEM's are so easy to drive I'm actually enjoying them alot with my iPhone6 plus using Tidal stream (offline when on the go).
 
Testing these earphones with my Burson Virtuoso I'm finding that the clarity has improved in a small way. The smartphone that is already with me 99.99% of the time has performed surprisingly well. I also tested these earphones with my Samsung Note 4 and I'll have to admit my iPhone6 plus has substantially better SQ  by a large margin.
 
Without considering price these earphones do have a very likable sound signature that is non fatiguing and provides "just enough details" to enjoy the music rather than analysing it with an over abundance of micro detail. There's certainly better out there but this is where $$$ and diminishing returns comes into play. When the Cost factor $$$ is in your head as you listen I think these PSB's are top of the game for the kind of SQ you get.
 
After auditioning the Klipsch X11i and slightly more expensive Shure 425's I was so underwhelmed it those two sound signatures. The free Apple earbuds that comes with the Iphone6 plus has similar "meh" sound quality. Listening to the PSB's the jump in SQ is very noticeable.
 
Now that I've listened to the PSB's extensively with all kinds of genre I do question if the Shure 535 (costs aprox $370 more than PSB) and if the price is worth the extra "ballpark" $400 dollars.
 
In my particular case IEM's are a nice to have...... for the price point I'm quite impressed and happy with the setup I now have. Never in my life I thought an iPhone could provide such a decent sound quality. Backgrounds could be blacker but for thousands of albums on tap "offline" I cannot complain. 

Are you using Tidal Premium or Hifi. If Hifi, how is it?

 

[AlanU]

 
Are you using Tidal Premium or Hifi. If Hifi, how is it?

 
I've been using Tidal for quite some time now. $20 cdn a month. I'm think the iphone 6 (plus,S) can handle 24bit/96kHz. I also subscribe to Google music play.
 
I do know that my Samsung Note 4 simply does not sound as good to my ears regardless of what type of resolution using tidal or Google play music.
 
I would not hesitate to buy an Astell/Kern jr. high res player for $500+ but for the sake of convenience and my SQ priorities for "on the go" listening...... The SQ difference is without a doubt there but having "offline" music via Tidal is much more simpler and economical.
 
I use Tidal a lot for my 2 channel system. "Hifi" setting is clearly superior to my Google Play Music's 320kbps.
 
For in home listening I'll use my Blue Circle AC Power conditioned  Burson Virtuoso with my modded Senn HD800 and HD650. For on the go listening I just don't  demand as much SQ so the iPhone 6 plus I have is proving very good sound for my application (I honestly can't believe I'm saying a smartphone for this application LOL!!!!).
 
Tidal is incredible value but Google Music has a better method of discovering similar genre artists and better playlists IMO. This is why I have both.  

 

[MacedonianHero]

   
So, my M4 U4s arrived a short while ago, so this is just very very early impressions, but with that caveat I will say that you are absolutely spot on with this comment.  The comply tips don't do it for me - the fit and isolation is supreme, of course, but the sound is just too dark and thick with them.  So I've swapped to the large silicones and oh my word do these things sound lifelike!  So natural, so unforced, so immersive.  Bass is not overpowering like others have said, not at all.  And neither is it lacking, as that Soundstageexperience reviewer commented. Nice package and build quality too.  Smaller earpieces than I was imagining them to be.
 
Of the hybrids I've tried - Trinity Delta and Fidue A73 - these are undoubtedly superior. By some margin. Of course, they are twice the price, but still....
 
Like I said, early days still of course, but I think these could be champions.

 
Hey congrats! I'm glad you're enjoying them...PSB did a great job with them!

 

[Toom]

Day 2 and am really loving the M4U4s.  The 'Room Feel' tech is not just marketing hype, it seems - Barton really does seem to have nailed a sense of instrument placement and frequency balance which is as true to listening to a 2 speaker set up in real life as I have heard in an IEM.  Superb stuff.
 
For those of you in UK who might be interested in these -  I got mine from Advanced MP3 Players, with 10% off using the code AMP22.   So £206.10 if you go for free shipping.