Lumu was designed to be compatible with all official Apple cases. There should be a distance of 2mm between the Lumu casing and the audio connector. If you think that the distance is smaller on your device please send a photo of the Lumu attached to your iPhone to firstname.lastname@example.org and we will assist you.
If you use one of the other case types and your Lumu does not fit on it you can also use an extender. The extender must be the 4 pole version.
You can use a short extender (this or that) or you can use an audio cable extender which can measure up to 1m (approx. 3ft) in length.
Here's another great 4 pole headphone jack extender.