Ok, have not posted an update since I first posted about getting my M9's. I was asked about my superbax cable and if I paired it with my m9's but the UE 18+ I have are the IPX version. M9's use the MMCX connections. Thankfully Sony's 4.4 cable is beautiful for being stock.
Onwards to the comparison between the Sony M9's and UE 18+'s:
To be blunt, they're very close. The differences between them are small for the most part.
M9 has better bass and that's really apparent. I noticed it upon first listen. I could actually feel some air being pushed around. These are the most neutral pair I've ever owned. I know the 18's are supposed to be neutral as well but in comparison to the M9's, the 18's are warmer and I do actually prefer the warmth when it comes to vocals. This is the one point over the M9's that I still miss. I'm not saying that the M9's can't render beautiful vocals (it absolutely does), it's just that the 18+'s really do seem to make vocals sound truer. There's a warmth in UE's offering that Sony's render colder. In defense of the M9's, there's a clarity in their sound that keeps making me think my 18+'s have a thin film of something getting in the way.
This is a completely subjective thought but when I listened to my 18's after using the M9's for a bit, my brain instantly thought there's some yellow tinted jelly that's coloring the sound in the UE's. Makes no sense at all but it's just something I thought of randomly.
Back to more concrete facts. Everyone has already mentioned how the treble and vocals are forward on the M9's and it's true. Guitar now has real depth and crunch to it. It's also very detailed. The way you can hear distortion from the fingers and picks plucking at the strings is super cool. I can hear similar detail in the UE 18's but it's fainter and less pronounced since the 18's are not forward on treble or even vocals. The M9's actually made it very obvious that the tonality of UE's offering is off. I'm not an expert but listening to the UE's now keep's making me question tonality. It's not accurate. This make's bring up the different ways these two pairs present a neutral sound. The M9's strike me as clean cut neutral. I understand now when people say they lack any real coloring which can come off as safe. I read this beforehand when I was researching a pair to buy but without hearing it, it's hard to understand how a sound can come off as safe or boring.
The UE's definitely have color to them-a sense of fun even. Which is a funny thing to consider when the M9's really do provide a realistic and fuller sound yet every day that I use them I admit they lack something the UE's have. Of course, knowing the UE 18+'s have 6 drivers vs the 5 on the M9 make's me wonder how Sony tuned these soo damn well. That was also another aspect that was readily apparent when I first listened to them. Sony tuned these to perfection! Considering the price difference as well, it's kinda crazy how much better than M9's are.
I listen to everything from classical European, hip hop, and 90's industrial to Japanese classical, pop, some country and pure metal. I go everywhere. The M9's truly have a versatility to them that the 18's always lacked. I agree that for the most part the M9's are the jack of all trades type but I do think they handle strings uber well. Classical seems to have this little extra kick to it. Instrumentals, especially if the source is using analog instruments vs anything digital, tend to sound exquisite.
Violins feel substantial as the bow drags across.
Guitars convey the weight of their strings, especially the little micro details from fingers and picks.
Anything plucked just vibrates with stunning detail.
Electronic music also sounds great but man, I cant deny that real instruments just carry more in their sound on the M9's. All the imperfections of analog go a long way on these.
So yeah, I love these. And yes, they pair great with my WM1A and the M9's actually don't need too much extra power. Usually they need on average 15 extra points of power. The 18's were usually played around 80/120 power level and the M9's tend to average 15 more at 95/120.
