I would recommend just sticking the the CX300 tips, if the tips that come with the RE0 are not to your liking. The one thing about the Senn tips is that they are pretty big diameter and still fit the RE0, so that the sound is not getting dampened by smaller nozzle on the tips.
TheT 400 (correction Shure Olives are too tight to get on the RE0 without risking breaking the RE0 nozzle -- and besides it dampens the nice treble of the RE0 (IMO), IF you ever get it on. Complies fit RE0 fine.
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