Nyaudio98,
I don't have personal experience with them, but the various Primaluna integrated amps seem to be a good match with the De Capo's from what I've read. Look at the used market for bargains there.
I also thought that the Manley gear I had (I had the Mahi mono-blocks but you could look for the Stingray integrated version) had nice synergy with the De Capos, but again, you'd be looking at the used marked since the prices at Manley have really shot up recently.
If you want to go SET, there are several options. You could probably get good pricing on an Antique Sound Lab SET if you call Tash at Reference 3A. You can also go to
http://www.commonsenseaudio.com/nirvanaamps.html
and check out their 300B SET, which is ridiculously low priced at $1550 with free shipping! Granted, I don't know anything about that amp beyond what's on the web site, but you get a satisfaction guarantee.
I would stay away from cheap, no-name tube amps from eBay, for sure.