I know that you can do that but that's a lot of gear (for me) to carry for listening to music on the go. If that was the ONLY way I could use custom IEMs, I'd rather just bow down to the Lightning adapter, since iPhones have really good DACs. (Wireless options exist, but not TRULY wireless ones).
I’m using the Fostex with IEMs (non custom) and the carrying case for the fostex is actually smaller than the ones that came with my custom IEMs. You also end up losing the wires so its literally just the two earbuds you need because you technically don’t need the case. So it’s net less equipment to carry.
Did you actually look at the items? All three essentially have you completely remove the wire and attach directly via 2-pin or MMCX, so it ends up just being two ear pieces. Of course it’s no longer hot swappable to 1/8 in physical plug afterwards.
