Preamp for Dan D'Agostino Momentum monoblock amps

Most users will surely choose Dan's own preamp, also an A+ product; but has anyone tried running tubes up front? Please share your experiences and preferences. Perhaps CJ GAT, Momentum mono blocks?
I haven't tried the combination myself, but since the amps have an extremely high input impedance of 1MOhm there shouldn't be any matching compatibility issues.

From Sterophile tests, not 1mohm but still quite high, tube and passive pre friendly.
"The input impedance was usefully high, at 200k ohms in the midrange, dropping to 160k ohms at the frequency extremes"

Cheers George
I tried ARC Ref 40 with Dag amp in house for 1 week. It was a great combination.
I got the 1MOhm input impedance spec directly from the manufacturer's website, and thought they should know.

"and thought they should know."

Yeah we all know how they fudge a little, in this case it doesn't matter or have any benefit to do so.

Cheers George
I have the Stereo version and use a Coincident Statement pre and it sounds spectacular.  I did change all my wiring to copper to get there, but what a difference.
This is probably more than a day late and a dollar short, but I am using an Audio Research Reference 6 to feed a D'Agostino Momentum S-250. It's hugely musical. I couldn't be more pleased.