I highly recommend Don Sach's 6SN7-based tube preamp. It betters any preamp I have had in my system and I have a boatload of them. Don sells the preamp directly so they are an extremely fine value. There are lots of review of the preamp on this and other forums.
Tube Preamps.....
I am running 2 GFA 565 Musical Comcepts modded Amps with Vandersteen 2ce v2. I am looking for a good quality tube preamp. With or without a built in dac. Should I stick with shopping for a used Mac? Or should I look at others also. Suggestions? Like to keep it under $3000. Could stretch to 3500. Thanks for your input.