I spent the last hours testing three different pair of CIEM.
Setup
DAC/AMP: Audio-GD NFB-11, Dragonfly Black, iPhone with stock 3.5mm adapter
CIEMs: 4x RAF-32873 series with Zobel (design by
@Ivan TT ), MASM v2 with resonator (design by
@dhruvmeena96 ) , Bellsing 6 with Zobel 22uF + 25 Ohm (zobel by
@Ivan TT )
Reference: Sennheiser IE80s with InAir tips, Sennheiser HD650
Whisky: Laphroaig 18yrs.
Conclusion first:
Best bass and overall performance: Bellsing 6.
Best mids and winner for classical music: 4xRAF, but only with a very good amp.
Best highs highs and best soundstage: MASM v2, but occasionaly shouty and not flattering to some voices
Detailed writeup:
4xRAF
Build: $32 for the drivers, but very hard to build. The build looks easier than it is, I lost 3 drivers in the process. That build was a lot of swearing.
Driveability: The iPhone is not able to drive the 4xRAF properly, even the dragonfly is struggling a little, but it sounds great with the NFB-11.
Sound:
Classical music is exceptionally good on the 4xRAF, "Samson et Dalila, Op 47: Bacchanale"
https://tidal.com/track/65160315 or Richard Straus
https://tidal.com/track/65160315 sounds best on 4xRAF, by far. Even when the entire orchestra is playing, you can still make out individual instruments and soundstage stayd intact. Phenomenal, even beating the HD650 in some recordings.
However, the 4xRAF is not very precise in the highs and in the bass. There seem to be peeks, valleys and resonances on both ends of the spectrum. In some electronic music basslines some of the notes jump at you while others get muted, for example Stimming the Origin
https://tidal.com/track/20484043 is very annoying to listen to.
Same with vocals, some voices stay intact, others get colored. e.g. Billie Eilish sounds great but Haley Reinhard or Roisin Murphy sound a little thin. E-Guitars get the "thin" treatment too (Billy Talent - Red Flag)
Conclusion: Nothing for on-the-go, because it's hard to drive. Phenomenally good for classical music and a coin-flip for everything else.
MASM v2
Build: ~$70 for the drivers. The build looks harder than it is, some wiring and a zobel and you're done. Tubing is easy with two separate drivers.
Driveability: Easy to drive, no problem to use from iPhone.
Sound:
Soundstage and air is phenomenal. However the signature is clearly tilted towards presence, imaging and soundstage. I grew up with the Sennheiser signature, so this is not my personal preference.
Electronic music sounds great, club-tracks sound like on a big open-air PA system, Jazz sounds great too.
However, some things do not sound good. Amy Whinehouse for example sounds tinny, and in classical music the soundstage breaks down if there's a lot going on. If it fails, then the highs get shouty and distorted. Sometimes to the point that they hurt.
Conclusion: Great if you love soundstage and presence paired with a great bass and don't mind the occasional shouty highs.
Bellsing 6
Build: $60 - $90 for the drivers, Soundlink varies pricing a lot. Build is quite easy - less wiring than the MASM but you have to stretch a tube over two nozzles.
Driveability: Very very easy to drive. Sounds good with everything you throw at it.
Sound:
Best bass and in my opinion the best balance of all the three. Amy Whinehouse sounds best on these, by far. Even better than on the HD650. Highs are very good too, not as good as the MASM but always pleasing.
The Bellsing 6 is behind the MASM v2 in soundstage and highs and behind the 4xRAF in classical music. But in contrast to the other two, it always sounds good. It never colors voices as much as the MASM 4xRAF and it never becomes annoying in the highs as the MASMv2 sometimes does.
Conclusion: Very warm set with a phenomenal bass. Slight weaknesses in the mids but a great soundstage although not as good as the MASM. Sounds good or great with absolutely everything I tried.
This is the first set I prefer over the Sennheiser for the range of music that I like.
