In terms of ARC, I don't know -- it just didn't touch me the way that the JR did. It was lovely and I even paired an ARC preamp with the JR amp -- so nice -- but overall I went with the Corus. The VAC was also gorgeous. I am just not sure that for all uses a tube amp is the way for me to go. The 625 does not need a preamp. It sounds amazing just with the Aeris in my opinion. BUT, I wanted the fullness that I think a preamp brings to the system. I was fortunate to receive one as a gift so that was a no-brainer for me. Still, I think I would have gone that route anyway. I stack the 625 and Corus so space is not an issue. Not saying this is a good thing to do, but it is better than not having them -- if I had more space and longer cables I might spread things out a bit more, but I don't. It also has to look good. So, whatever one you decide on is the right one for you. In this line up you can't make a wrong choice (in my opinion). Also, you might start with the Aeris and 625S -- then when your listening plateaus -- add in the Corus (or tube amp). I find the PSU is going to be a welcome addition to this set up.