Could use some help with a tough match


I currently have a pair of Threshold SA 1's which have been completely rebuilt. My challenge is to find a preamp to create the right synergy with my Sonus Faber Amati's. I would like to try a tube preamp but the Threshold's input impedence (75k) and its unbalanced inputs are making it very difficult to find a match. Has anyone out there had any success running the SA 1's with a tube preamp ?
dcramsay
Thank you for all of your great feedback. What started this thread is I was looking at a BAT VAT 51se so called BAT and Threshold directly to discuss compatability. What prompted the call was the Stereophile review of the BAT which cautioned against matching low inpedence input on some amps with the BAT's 410 ohm balanced output. BAT said that it should be ok but running a balanced unit into unbalanced amps would certainly would not allow me to get the maximum performance the preamp is capable of. Threshold told me I would not have close to the 10x ratio that is the general rule of thumb for a good match. Also that a lot of tube gear had high output impedence. I must admit that the feedback I am receiving from each of you is different so I am a little confused. I really appeciate the input because I need to narrow the field a bit before I can shop for the appropriate preamp. My SA 1's have always served me well ( Maggie's, Thiel's) which is why I really wanted to match them up. I currently have 2 Threshold pre's but time to upgrade to current technology (a remote control :}
Well Threshold is right, you will not have close to a 10X ratio. You have a 183X ratio (75000/410). What they didn't tell you is that 10X is the MINIMUM recommended ratio. The higher the better. 183 is much better than 10, so no worries.
Obviously BAT gear was designed to run balanced. You can run it unbalanced, but you will not get optimum performance. This has nothing to do with the impedance matching though.

Cheers,
John
John,
If I understand the conversation correctly with Threshold if I installed balanced inputs it is not a matter of straight math. The input impedence of the Threshold's would be approximately 600 ohms balanced. That was the issue. Certainly not an engineer but that's the feedback I received.
I'm sorry, I must have missed the earlier post where you stated the 600 ohms balanced, not recommended with a tube preamp. So obviously you can only run SS preamps balanced. If you want a tube preamp you will need to run it unbalanced, obviously.

John
John,
Really sorry if I came across poorly. I certainly did not mean to come across negatively and truly appreciate and welcome your suggestions and feedback. This is my first time posting here because I am trying to learn ( at least a little... In all these years I have never owned a tube preamp, or a remote control :) on my systems so I am really venturing into new territory . My general principle has been simplicity of design (less parts, loops and interfaces) = less noise and better sound. I think the challenge for me is the number of quality components that are going to all balanced inputs and outputs with some making a concession to RCA outputs and inputs for convenience. ie in Stereophile measurements of the ARC reference 3 it was pretty obvious that measurements were better in balanced mode. I know measurements don't always tell the story but it's a start.
So thanks again for your feedback it really is greatly appreciated !

All my best,
Don