Bit of thinking out loud on a recent comparison session.
I've now been comparing EL-8 Closed, SINE, and Blue Ella (another planar magnetic headphone)(,and Mobius). It's been interesting, and I intend to only keep one in the long run due to budget restrictions. I've spent the longest with SINE headphones (more than one pair) for the past year, so I'm super familiar with their sound signature with external amp/DAP and with Cipher cable. I'd say the only thing SINE wins in for me is their light weight and discrete appearance. EL-8 has much fuller, more detailed sound, greater soundstage. SINE sounds almost tinny to me sometimes in the treble on some songs, despite a dedicated powerful external amp. Soundstage is really small, even when apparently expanded with a good DAP and amp. Mobius was a gift for my significant other and is a permanent addition to our household due to its functionality and great sound. It doesn't quite reach the excitement and fullness of SINE/EL-8 with a good external amp, but is technically excellent with great low bass detail and extension--much better than the SINE's. My favorite in terms of the sound is probably EL-8 Closed (post-revision type) paired with an external amp, but Blue Ella is a close contender. Their tuning is very different. Audeze does a very forward, clean, detailed, more in your face kind of sound with prominent mids and treble. Blue went for a more rounded sound with non-fatiguing rolled off highs that you can listen to for hours and not tire of.
Also, Ella has a fully passive mode and a built-in amplifier that one can turn on to reduce effective impedance, and also an amp+ setting that boosts the lower end with a built-in EQ--the latter can give a good boost to some songs, but at other times feels too warm with too-reduced mids/high end/presence. My favorite is definitely the regular active mode if not using a good external amp. Ella can sound really good in active mode + better phone like OnePlus One (has pretty good DAC, etc.) eliminating the need for external amp. Ella is still large, heavy (weighs about as much as EL-8) and really attention-catching, so going out with it may require a fair bit of self-confidence. Not that going out wearing EL-8 Titanium isn't similarly attention-grabbing, but the SINE is very discrete. EL-8 and SINE need an iPhone/iPod to use in-wire amplifier, which is basically useless for those of us with Android phones--and personally I prefer other amps to the cipher sound signature.
I'm kind of going between "Do I keep the one that sounds best?" (EL-8 Closed, but that's still TBD). "Do I keep one that's the most discrete, even though at times the sound from it really bothers me?" (SINE) "Do I keep one that's the best all-arounder but not that discrete?" (Ella) In some ways Ella sounds best to me where EL-8 and SINE can feel almost sibilant in their overload of top end presence.
