[fooey]

I own the following IEMS : Westone W40,  Dunu DN1000 and Shure 535s and for a while I've been thinking of upgrading to something better.
 
Last year when I was in NYC I popped into B&H and auditioned the Shure 848s. When I listened to them through my Samsung Note 4 for a short period of time, I didn't notice much of a difference in sound quality over the W40s I had with me. When however the shop assistant let me use the Astell & Kern AK120 as a source playing DSD(?) files, the sound coming out of the 848s was sublime. I left the store without making any purchase.
 
A few days back, a colleague of mine was kind enough to let me use his 848s for a few hours. Again, using my Note 4, I didn't notice any significant difference between the Shures / Westones. I played a variety of 320kbps MP3s and FLAC files.
 
So what's the bottleneck here? Source, media, IEMS or my old ears? I'm sure that a lot of folk here would say that the 848s kill the W40s.
 
Oh, forgot to say that when I also used my AK100 to compare the two IEMs, there was still not much in it for me.

 

[truckdriver]

You should provide your own answer. You say you had the W40 with you when you heard the sublime sound from the AK120. If you plugged the W40 in and it was still sublime then it was the player or file type. You are the only one with the ears to know for sure.

 

[alffla]

I wouldn't necessaaarily say the 846s "kill" the w40, since perhaps you prefer the sound signature of w40.
for me, i would definitely prefer the 846 since IMO they replicate every frequency with much more fullness, - westone's offerings often have "polite" sound signature with a relatively recessed bass and warm mids and far reaching clarity in the highs, while the 846 provides a hugely impactful and slamming bass sound with much more forward mids, and compared to the w40, slightly recessed highs.
 
Personally, i think every step of the audio chain has a bottleneck, with your ears probably being the first bottleneck. if you are unable to differentiate the difference between $9 usd and $900, then there's no point in proceeding further
 
however, i think the biggest difference in sound is found equally between sound quality of your media and IEMs, followed by music player.