Audio Note M6 vs M5 - M6 is a older model

I have an offer to buy an Audio Note M6 with older power supply and an M5 with the newer (Galahad) power supply. Could anyone tell me which one would be a better buy ?

If I decide to upgrade the M6 to the new power supply, what will be the approximate cost of the upgrade ?
Why don't you call Audio Note, or one of their dealers and ask them?
Get the OTO Integrated amp. Get An speakers (AN-K, J or if you got the bucks, E). You will be very happy. The OTO's are really intended for AN speakers, or at least high sensitivity speakers, which the Eggs are not.