Short update: I'm going to keep the i4. Using the Anker usb-c to Apple adapter and the wired cypher cable i get pretty good sq. The only thing that to my ears is disappointing is the timbre. But this is compared to my reference hp (Stax sr-009s).
The i4 is a great portable iem for my use case: not for commuting or listening in noisy or public places, but for tooling around my home. A full-size estat is not portable after all!
There really is no alternative to i4, except Shure KSE, other than Audeze and Shure, all other top contender IEMs are balanced armatures, with significantly higher distortion figures than Planars and Electrostats.
You mentioned that timbre is the only issue compared to your Stax 009. The 009 are widely considered the best headphone for any money, over the ear full size, so this may not be fair fight. Still, by timbre, do you mean frequency curve? That would be easy fix, dial in EQ for i4 what suits you, maybe timbre means something different.
i4 need proper DAC and amp, Cipher is not it. Cipher is quick fix, and guarantees flat frequency response, unfortunately you are stuck with iPhone amplifier, probebly not state of the art as far as amps go. I imagine Class A desktop amplifier is significantly better than iPhone output. Sabre chipped desktop DACs are very likely significantly better than Audeze Ciper chip. Just like Stax electrostats, in order to hear what i4 can put out, the very best electronics up the line are needed, and iPhone is probebly not it.
How would you compare distortion of i4 and your Stax 009? Distortion and lack of it, also known as 'transparency', 'airiness', 'looking deep into the soundstage', 'veils lifted', 'pinpointing the instruments in orchestra', 'lack of listening fatigue', 'like hearing my favorite recordings for the first time'.
With proper EQ setting, proper fit in ear canal, with proper amplification, how much are LCD i4 behind the Stax 009, you feel?
I have listened to Stax 009s extensively, for hours and hours, over many months in Bangkok Audeze and Stax dealer's showroom, Tidal and TOTL desktop DACs and amplification as source. I have a a strong opinion about Stax 009 vs LCDi4, but you first!