Thanks to everyone for their opinion and feedback, very helpful. An opportunity kind of made my mind up for me as a fellow on Canuck Audio was selling a VSi75 with a set of KT120' and KT150's with only a 100 hours on both. His unit came with the 120's but he contacted AR and they said there was no issue using 150's so he bought a very expensive set from them; I think I will go to the Tube Store or Upsacle when I need new ones. The only issue now is to get a Cardas XLR to RCA adapter as I am currently running a balanced interconnect from my Audio Analogue Settanta to me Ayre P-5xe; no balanced inputs on the 75.
Cheers.