KLH MODEL NINE ELECTROSTATIC SPEAKERS.

I would exercise some caution with loading a vintage amp. The amp probably needs to be recapped and I would not subject it to anything other than one pair of speakers at a time. I once burned up an old Marantz power amp playing around with multiple speakers.
You should be able to get satisfying volumes even at 16 Ohms. It's a pity that these speakers are not being driven by tube amps, which do really well with higher impedance speakers.

Sounds like that would work. You can jumper the wires or use double runs. Both ways are pictured here.

http://www.bcae1.com/spkrmlti.htm

Perfect, so i'll connect them in parallel and the load will go from 16 ohms to 8 ohms which is good.

You may want to reach out to Janszen, whose father designed the 9. His company, in Ohio, offers restoration services, and he may have some tips on how to check and bring a pair back into service to avoid problems.
They were glorious speakers in their day- I fondly remember double pairs being driven by Marantz tube amps back in the late 60's. FWIW, there are a couple of owners on this forum who may chime in with other tips based on their actual experience in owning and running them. I still have multiple pairs of Quads, but would be reluctant to press the old pair back in to service without having them thoroughly gone over first.

Here is the link to janszen:

http://www.janszenloudspeaker.com/JansZen%20-%20KLH%20Nine%20Refurb%20&%20Upgrade%2090202.pdf