[pohoda]

iDamp
iShrink
iNsinuator

 

[zomgpront]

Tranquility
Fidelity
Mollifier

 

[trick]

I'm not sure if these have been suggested, but:
 

1. iSmall
2. iSoft
3. iLight
4. iLow
5. iResist
6. iFly
7. iMacro
8. iNarrow

 

[ModMax]

non i-Names (Feature Names):
1) XSilence (A play on the word excellence)
2) XSilent Sound
3) Sound XSilence (SxS)
4) XSilence in Sound
5) Silence of the IEMs
6) Back to Black (B2B)
7) Back in Black (BiB)
8) XSilencer
9) XClarity
10) IEM-Q (Quiet IEM)
11) Super Sensitive Silencer (S^3 aka S cubed)
12) IEM Clarifier
13) IEM (In-Ear Mollifier)
14) IEM Anti-Venom (Hiss Reduction)
15) DHR (Dynamic Hiss Reduction)
 
i-Names:
 
iEM12 (or iEM-12 or iEM 12)
iEM24 (or iEM-24 or iEM 24)
 
iEMPurify12 (or iEMPurify-12 or iEMPurify 12)
iEMPurify24 (or iEMPurify-24 or iEMPurify 24)
 
iEMClarify12 (or iEMClarify-12 or iEMClarify 12)
iEMClarify24 (or iEMClarify-24 or iEMClarify 24)
 
iDeNoise12 (or iDeNoise-12 or iDeNoise 12)
iDeNoise24 (or iDeNoise-24 or iDeNoise 24)
 
iClarify12 (or iClarify-12 or iClarify 12)
iClarify24 (or iClarify-24 or iClarify 24)

 

[bluemonkeyflyer]

iCan Whisper

 

[Dr4Bob]

SiLENT SERViCE

 

[DisCHORDDubstep]

Izanagi (from Japanese mythology, which, as luck would have it, has an I at the start of the name, and it sounds cool... And he executed the fire god, named kagu-tsuchi... And fire hisses so...), Icaramba, (clever name. Thought of the Spanish phrase aii caramba, and there was a name!)Iguana, (lol) Ideal, Illusive, Imagine, Immortal, Inertia, Ideal, Impede, Irreal, Influx, Isopod, Iris, Ionize.

 

[karzai]

Synapse
Windbreaker
 
Not saying anything about attenuators but this one sounds fancy:
SimpliFi

 

[Rzybon]

LessMess

 

[Ishcabible]

iMongoose (get it? Kills snakes...hiss...hah)
 
But actually, if it's a separate product, it'd make sense for it to be iSomething because everything else except the Gemini is iSomething. Maybe iMask?
 
iShcabible would be cool too.
 
But if you'd be fine with exploring outside of the iSomething range, ClearFi (although Acer seems to be using that name for wireless stuff), IEMate (technica iEMate but nobody uses iEM anymore)

 

[dwong]

iFi iShy (my favorite)
iFi iTympani (as in tensor tympani, the muscle in the ear that dampens sounds)
iFi iDimpani
iFi iDim (iDimplify?)
iFi iDimmer
iFi iDimine/iDimini (as in diminuendo)
iFi iDamplify
iFi iPure
iFi iPurify
iFi iRarify
iFi iPurge
iFi iAerify
iFi iMitigator/iMitigater/iMitify
iFi iModerator/ iModify (moderate)
iFi iCushion
iFi iSilk
iFi iLucidify
iFi iCrystallize / iCrystal
iFi iMellow 
iFi iCloak / iCoat
 
Specifically for hiss reduction
iFi iBadger
iFi iHoney (honey badger)
iFi iCobra 
iFi iHawk
iFi iEagle
iFi Average Joes (https://www.youtube.com/watch?v=VlsWsqQpWDQ​ ) 
iFi iAntidote
 
 
I could go all day...

 

[hiftenthuser]

Got to be iTTENUATOR  !

 

[Rzybon]

NoHissHiss
 
Shhiss

 

[Turrican2]

iDongle
iHelper
iVolumator
iDesensitise
Rect-iFi
iBorg - Resistance is not futile
JuiceBooster - boost the juice on the iCan
DDoS - the dangly dongle of silence
Volumiser
Turn it up to 12!
The ranger
A-Tenuate
D-Sensitise technology
D-Sense-iFi technology (DST-12, DST-24) (easy for labelling on the ican if integrated)
ESP - Eliminate sensitivity problems
aural-pleasure-enhancer - 'the ape'
The silver bullet

 

[65535]

I went through a few pages and didn't find it.
 
I thought you might call it the iMpede, but that's pretty long and someone already suggested it.
 
How about the 
 
iFi iMp
 
Seems appropriate, small impedance matching adapter.