I had the v5 in Cabillas cups and they sounded great even before any amount of significant burn-in time. This was my 4th pair of "Grados" and every single time I ended up selling them just because open phones don't work in my household/office (don't know why I keep going back to new builds!). It's a shame really because they sound great. I just can't have the perfectly quiet household to truly enjoy them (and not annoy people around).
Until then, it's back to closed phones for me.