Well, I can tell you what preamp not to buy-and that would be the Mcintosh C2300. I also own the Defy 7 MKII amp and I currently have a C2300 on audition in my system and I don't think it will be staying. I can tell you that the Counterpoint SA-5.1 is an outstanding match with the Defy. The only reason I was considering something else is that I was hoping to retain all of the sonic virtues of the 5.1 while adding more inputs including balanced ones and the cool remote features of the 2300. That is clearly not going to happen in this case.
Back to your question-if you can find a Counterpoint SA-5.1 (and good luck, they don't come for sale very often)and preferably one that has made it way back to Michael Elliott (the original designer)and had the line stage and phono stage upgraded, don't hesitate to jump on it. You didn't mention whether you need a phono section or not, but the SA-5.1 has an outstanding phono section built in. If you are going to use low output MC cartridges, you will need a step-up device. Again, I can tell you that the combo of the SA-5.1 and Jadis Defy 7 MKII is magical. Of course I would love to hear a Jadis preamp but I haven't had the opportunity. I have learned my lesson the hard way before and that is to never sell my SA-5.1 unless something else can prove it is better in my system. That hasn't happened yet. As for the Classe DR-6-forget that. I owned one and quickly got rid of it. No pun intended, but it is not in the same class as a good tube preamp let alone the 5.1.
By the way, Michael Elliott is selling brand new preamps under his Aria brand which in my opinion are based on the SA-5.1 circuit but with much better parts than were originally used. He has added a choke in the power supply and a trick power supply for the tube filaments to allow switching between 6 V and 12 V tubes so you can drive yourself crazy tube rolling. His new preamp is custom built to order and is available for close to your full tilt budget. When 5.1 preamps come up for sale, they generally go for around $1400 and more if they have had the line stage and phono stage upgraded by Michael Elliott. They bring less money than the SA-5000 which is kind of funny. People think that because the SA-5000 is newer than the 5.1 and sold for more money that it is better than the 5.1. They couldn't be more wrong. The 5.1 smokes the 5000. Good luck and I would love to know what you end up with.
Back to your question-if you can find a Counterpoint SA-5.1 (and good luck, they don't come for sale very often)and preferably one that has made it way back to Michael Elliott (the original designer)and had the line stage and phono stage upgraded, don't hesitate to jump on it. You didn't mention whether you need a phono section or not, but the SA-5.1 has an outstanding phono section built in. If you are going to use low output MC cartridges, you will need a step-up device. Again, I can tell you that the combo of the SA-5.1 and Jadis Defy 7 MKII is magical. Of course I would love to hear a Jadis preamp but I haven't had the opportunity. I have learned my lesson the hard way before and that is to never sell my SA-5.1 unless something else can prove it is better in my system. That hasn't happened yet. As for the Classe DR-6-forget that. I owned one and quickly got rid of it. No pun intended, but it is not in the same class as a good tube preamp let alone the 5.1.
By the way, Michael Elliott is selling brand new preamps under his Aria brand which in my opinion are based on the SA-5.1 circuit but with much better parts than were originally used. He has added a choke in the power supply and a trick power supply for the tube filaments to allow switching between 6 V and 12 V tubes so you can drive yourself crazy tube rolling. His new preamp is custom built to order and is available for close to your full tilt budget. When 5.1 preamps come up for sale, they generally go for around $1400 and more if they have had the line stage and phono stage upgraded by Michael Elliott. They bring less money than the SA-5000 which is kind of funny. People think that because the SA-5000 is newer than the 5.1 and sold for more money that it is better than the 5.1. They couldn't be more wrong. The 5.1 smokes the 5000. Good luck and I would love to know what you end up with.