help hooking up electrostatics 2 sets at a time

The Rowland amp, which is very stable at lower impedances, should have no problem handling two sets of Accoustats. Just run two sets of speaker cables from the amp to the two sets of speakers.
The Accoustat is a fairly civilized speaker, as it does not tend to go below 3.5 ohms. Some 'stats go down to 2 ohms, which can cause many amps to "fart in your general direction" and shut down on you! Running two pairs off that kind of amp will make them run away from home, never to return...)

Running two sets of speakers in parallel will halve the impedence. Therefore the amp will "see" 1.75 ohms. check with Rowland and see if the amp is stable into that low a load. If you are not using them in the same room, why not use a speaker selector switch?

Agree with above, do NOT connect these two pairs in parallel UNLESS you talk to Rowland first and get their firm OK. Swampwalker explains why.

If you much play 4 spkrs simultaneously you may have to choose an amp that provides for low impedance stability OR mod yr own for that purpose. Or, buy a second model5, of course!