Personally I think the JR absolutely need some power to get going, otherwise they can just sound a little boring. One muscle amp that can be had fairly cheap is the Innersound ESL 300. I tried it with my pair and while I ended up liking the sound with a higher priced pair of Parasound JC-1s, the ESL 300 had the power the JRs needed.
My first choice on your list as is would be the Plinius, only because I know it to have pretty high power for an integrated.
My first choice on your list as is would be the Plinius, only because I know it to have pretty high power for an integrated.