A wine-loving friend of mine reasoned as such:
if you're going to soak the cubes in wine, the wine will take up oxygen and "spoil". Sure, your cubes will taste like wine, but the catch it that they'll taste like oxidised wine which is probably not what we want.
He proposed simply adding the cubes, and blending with freshly openend wine at bottling time.
Soaking cubes in wine for two years...now I can't imagine that not having a negative effect on the wine flavour, but perhaps the oak flavour have become so powerful that the wine flavour doesn't register much. In which case, any cheap ass wine would do, right?