What would you choose among these to amp?

I am buying a new amplification set for my system, and I now have my options narrowed to basically four:
Roksan kandy integrated (1100 dollars)
Adcom 5800 + Rotel RC972 preamp (1000)
Adcom 7000 integrated (1000)
Marantz SR-18 receiver (900)

Considering the closest upgrade I have in mind is a subwoofer, and I will use the amp to drive a pair of JBL S310II, mainly for music usage, what would be the recommendation?
A used Aragon amp along with a Creek or F.T. audio passive can be had in that price range, this would in my opinion pretty much blow the doors off of anything on your list for quality of sound for money spent. The Aragon's match up very well with passives.
Soggod51 has a very nice recommendation. Aragon products can be had used at a very nice price and their quality is very good.

You can also consider a McCormack DNA-1 (around $800-900) used with a TLC-1 (around $350-500) used too. The Parasound Halo P3 preamplifier is having great reviews and I saw one for $600, combined with a McCormack DNA-0.5 should be a great match.

Good luck,
I would not use an Adcom 5800 with any speaker of a vented design. I have no experience with any of the other devices mentioned. Sean
Maybe you need to go back to the drawing board on that one!Not trying to be funny but there's plenty of other products to consider.I'am with SoGood and jahaira on that!

Good Luck!