Does my 2nd hand 252, 300 and CDX2 still need burning in if so how long? And is the 555ps dr the best upgrade idea?

This is my first Naim system and my first time any forum period, so please excuse my choice of question as i guess its been asked many times. As its 2nd hand does it still need to be burned in? I am thinking of going straight for the big big jump adding and a 555dr ps as i think it needs a little something, thats not taking away the fact that it allready sounds good i'm just greedy. Any ideas as to wheather its the best idea? I am one month in and eager. Regarding speakers i know the proof is in the lissoning, i am currently using Rega's p5 which is going asap and i am looking to switch to Bower and Wilkins 804 D3 has anyone used this combernation or have any idea as to if its a good partner? The cable i use is Chord Company's Sarum for speakers and interconnects it sounds good and i'm happy with that...