Well, I recommended this once before, You didn't say anything in that thread, but it answers what you are looking for.
http://www.coda-continuum.com/product/index.php
I've never seen a preamp with adjustable input impedance.
Coda is a group of engineers that were part of the design team for Nelson Pass at Threshold. They do have a different flavor than Nelson's current stuff, but these guys are very competent designers. The 07X preamp can hold its own with the best solid state. Might not be your favorite flavor, but its worth checking out and they have auditions, if you don't like it, it will only cost you shipping cost to send it back.
I hope this helps,
Tim
http://www.coda-continuum.com/product/index.php
I've never seen a preamp with adjustable input impedance.
Coda is a group of engineers that were part of the design team for Nelson Pass at Threshold. They do have a different flavor than Nelson's current stuff, but these guys are very competent designers. The 07X preamp can hold its own with the best solid state. Might not be your favorite flavor, but its worth checking out and they have auditions, if you don't like it, it will only cost you shipping cost to send it back.
I hope this helps,
Tim