It is all a matter of taste. I use a PS Audio UltraLink II and love it about $500.00 used, a Cal Delta transport, about $400.00 used, and a Melos Maestro tube preamp. There is a used one on this site for $1100.00. Other preamps beside the very good Morrisson http://www.surpher.com/MORRISON/ are some tube units. Zen preamp is very good http://www.decware.com/preamp.htm and also Wright preamp WLA12A http://www.wright-sound.com/ These three companies make excellant products and they do not cost over $1000.00.
The best used preamp and d/a converter
My system consists of Revel's F-30 performa's and dual classe 100 amps, and a old Rotel Rsp960ax preamp and a denon cd player. I am definetly limited by the last two on that list and want to upgrade these components. I have been told the cp-50 or cp-60 would be a great preamp for my system and the theta IIIa converter with the data basic II transport would make a very nice system. I was just wondering what everyone else's thoughts are on this. Other recommenadtions would be helpfull. I am looking to spend about 1600 on the preamp, 900 d/a, and 450 on the transport. Any info would be appreciated. Thanks