I'm really surprised about all the "flat" comments about EL-8 Closed (post-revision)/Titanium. I've listened to both of those with a Cayin C5 mobile amp in high gain mode, and usually with +bass boost to round it out. Nothing flat about it! Really detailed, powerful, and has plenty of excitement. I am NOT a fan of the Cipher cable tuning in general and prefer to use another amp/DAC.
Sine is more upper-mid/high-forward and with a more compressed soundstage. I've used SINE for a long time now and have had a good amount of time with EL-8 and Mobius. Another planar I've been listening to is Blue Ella - now THAT headphone is laid back for sure. Plenty of bass, but the upper mids and treble seem all scooped out, so apparent detail is lower than Sine and EL-8. Easy to listen to, easy to drive with a cell phone and built-in amp combined, but I miss the detail emphasis of EL-8 and SINE when listening to Ella, because I'm so used to the sound from the former.
Sine: small, light, discrete, has the best passive noise isolation when outside. Compressed soundstage, lower detail in the low end, bit harsh in the high end for recordings that are more treble/high-end-heavy.
EL-8 Closed/Ti: more balanced vs. Sine, much larger soundstage and emphasis of small detail (like an artist shifting a chair in the background), overall larger more immersive sound. Heavy, Titanium model looks silly in my opinion (who decided the bright silver "O" on the black background was an upgrade over the black/wood version?), worse passive sound isolation than Sine and so less mobile, higher impedance than Sine needing more amplification. Low end not as powerful but not much less, while gaining greater extension and sub-bass detail. Sine just kind of rolls off at the sub bass level: you can hear things happening in that region, but they are quiet/not emphasized. So far Mobius reigns supreme over both Sine and EL-8 Closed in the sub-bass quality for me. Bright in the high frequency region which gives the airy presence but are actually sibilant (at least my Titanium unit) with some tracks, which is a bad thing. Sine is almost never sibilant.
I personally prefer and have more appreciation for the sound from EL-8 Closed (post-revision) than from Sine, all other equipment and songs being equal.