The below info is direct from the late Bascom King when i was looking into the preamp and asked the same questions to my dealer. Direct from BHK: "No problem! 10K is an easy load. it can drive loads down to 1K. There are no series output coupling capacitors to roll off the low bass either."
Also running all my gear balanced and tested the Coda 8 balanced as well.
Re. the 250 vs Coda, frankly I would be super happy with either. By a touch sweet I meant its not dry or analytical. It will dig in and show up tremendous detail and depth, just not in a sterile way. Its polished like a top Hegel kind of sound. It might not have 100% of the "bloom" or kind of halo-space of the tubed BHK but its insanely good and from the moment you have the pre with tubes in there should be totally fine. I am contemplated actually to change to the Coda as in the future will be driving electrostats. BHK has nearly twice the filtering capacitance of the No.8 but 1/3 of the 8’s power supply. Would joke that the Coda has its own gravitational pull! hhaha.