I used to be very paranoid about oxidizing wine during racking. I use carboys and very carefully avoided any unnecessary exposure. This made racking a ***** because that means I need to have a few empty carboys at the ready. I have recently started racking into a bucket, adding my K-meta or tannins, rinsing the carboy and then racking back into the carboy. I do not detect any degradation in the wine and the added oxygen exposure is probably helping. I am not splash racking when I do this, just trying to be careful not to bubble the wine too much. In my view it is not all that different from when I am blending wine just before bottling. Essentially the same process. I am not someone who does a lot of racking anyway, but if this was done 4 times in the life of the wine maybe there would be noticable oxidizing.