unless you have 2 similar iems side by side for a blind test comparison, its hard to judge burn in results.
opened up my vsd2s to test. the size is the middle child of westones um1 and shure 215, bigger than the um but smaller and lighter than the 215s. sounds pretty good out of the box as stated above. presentation wise, if an16/gr07 is a long tube in your ears with little depth, the 2s is more of a circular shape soundstage which is more balanced imho.
The upper mid range is terrible as of now, it seems the vocals were boosted so much that it actually sounds like its floating above the other frequencies and in your, stark departure from the an16 first impressions. For me it means i cant concentrate on the treble at all cause i hear is just that boosted upper mids. Getting a headache just from listening, will let it burn in and hope for the best.
The boosted upper mid range doesnt take away the fact that the whole presentation of the d2s is impressive for the price with wonderful lows and all round separation.