I'm not sure where to send you regarding amps, though there are many, many options. Someone more familiar with your speakers may need to weigh in, and Evelick's advice is right on.
Another suggestion is to look at the most recent tread on the SL2000a (link below) and make sure you have a good tube complement. It's wonderful with the right tubes, very average with the stock tubes. I recommmend an Amperex Bugelboy 5AR4 rectifier (this will give you the biggest improvement), and Mullard 12at7s.
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1157186575&openmine&zzBdgregory&4&5#Bdgregory
Another suggestion is to look at the most recent tread on the SL2000a (link below) and make sure you have a good tube complement. It's wonderful with the right tubes, very average with the stock tubes. I recommmend an Amperex Bugelboy 5AR4 rectifier (this will give you the biggest improvement), and Mullard 12at7s.
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1157186575&openmine&zzBdgregory&4&5#Bdgregory