Well, the 8:1 turns ratio transformer at
http://www.jensen-transformers.com/datashts/110khpc.pdf would almost do
it for you. It falls off a bit at the high end. But with it, you
could go down to less than 10Hz. That might be fun. What core
material were you using in your calcs?

I really think you're being too cautious about preamps. But again, my
point is that you can put the effort into the loop, put it up, and then
play around with different feed methods. If you do use a feed line and
leave the tuning capacitor at the antenna, you won't notice any
significant loss in the line. Reg will try to "sell" you one of his
programs for looking at how the line transforms the impedance, but I'd
just use a Smith chart program myself. Much more educational, to me,
than just seeing numbers. If you want to try tuning at the receiver
end, use heavy wires in the line: their resistance adds to the
resistance of the loop itself, lowering the Q. But with the capacitor
at the loop, the circulating currents stay out there, for the most
part. You could add a small variable at the receiver end, to do fine
tuning. You may well discover that's an advantage...it's a pain to try
to tune the loop without being able to listen to the signal...

Cheers,
Tom
(about to bow out of this...time for you to go try some things.)