Help with Impedance

10 to 1 ratio is a minimum. You are in good shape. The problem with high impedances is that the signals carry very little current and you are more susceptible to ground loops. Imbalances with respect to ground become critical. A twisted pair of wires (no shield) may be your best RCA interconnect option. Preferably fully balanced XLR should be used.

There's a bit mor to it than that but I'd vote it'll be OK. The gain of the preamp and amp will come into play. Naturally the speakers eff is a consideration too.

At most what will happen is the volume knob might get turned up a bit more so. If the pre has 17db or better, and the amp has 20db or more, you ought to be fine I'd think aside from the knob going up some.

There's more info around here on just this topic take a look at this one:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1222315177&openmine&zzBlindjim&4&5#Blindjim

... there are more.

Good luck