So I found a nice way to keep alternate tips from slipping off the sound tube of the Sennheiser ie800`s. If you`re wondering what those tips are, they are Ortofen spinfits, you can see my sound and ergonomic impressions (installed on my ie800`s) here: https://everydaylisteningblog.wordpress.com/2016/03/25/spinfit-tips-cp100-review-big-ergonomic-upgrade-comes-with-big-sound-changes/
I had some foam stuffed Sony hybrid isolation tips lying around, the foam started separating from the tube so I removed the internal rings and put them around the soundtubes of my Spinfits. It`s fairly easy, you just invert the tips, slide the rings up the soundtube to the very top and slide the rings down around the nozzle like a clamp for a tight fit.
^For visual reference, there is a plastic ring that runs around a notch in the sound tube. Below is a picture of the foam and ring and beneath that, a photo of the removed ring installed on the spinfits.
They are now seated very snugly on the sound tubes of the ie800`s and seal really nicely, unfortunately you can`t use the foam itself for extra isolation since the soundtube of the Spinfits is too long and the rotating mechanism is in the way. This should work with any 200 size tip (Spinfits, Sony Hybrid, etc). Hope that helps some people having fit issues out there, the spinfits fit well and sound quite close to stock. So with this mod you can use your favourite tips to improve the fitment of your ie800`s and even modify the sound.