Could use some help with a tough match

Second (or third) that 75K input impedence would not be a problem for a tube pre-amp.

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.