The only thing that would prevent you from using the Church Audio preamp with your PS-2, is knowing if your PS-2 has a DC blocking cap to prevent any voltage entering from the preamp. Therefore, I wouldn't try this unless I absolutely knew. I have the same "1/8th jack mod" PS-2 though. By the time you plug in the 1/8th jack from the PS-2 into your Edirol R-09, the signal is already unbalanced and a good opamp (much like the 9100 providing 20db of true gain) could be used to boost it. In fact, that is what is happening inside the R-09 when you turn up the gain anyway with just the mics and PS-2.
Alternately, what you could do is plug your mics and PS-2 into the "mic" jack on your R-09. Turn plug-in power "off" and set the mic gain to "low". I would not tape anything more than someone strumming away on an acoustic with this though.