Well, since the specs of your preamp seem to be "unavailable" online and you don't list the gain figures for each stage, I can't give you a definite answer.
Does each stage work concurrently...both controlled by the common volume control? If not, your idea won't work; and if so, the active and passive sections would need to have the identical gain spec, which is highly unlikely.
So I'm highly doubtful that your idea would work.
Why don't you simply find a preamp with two pairs of outputs running off the same preamp circuit? There are plenty of those around... I have a B&K Pro 10 that has both active and a buffered passive modes and sounds quite respectable. They are quite inexpensive on the used market and have two pairs of RCA preamp outputs plus one Balanced XLR pair. You could easily power two separate stereo amps with it and have your choice of passive or active modes.
Does each stage work concurrently...both controlled by the common volume control? If not, your idea won't work; and if so, the active and passive sections would need to have the identical gain spec, which is highly unlikely.
So I'm highly doubtful that your idea would work.
Why don't you simply find a preamp with two pairs of outputs running off the same preamp circuit? There are plenty of those around... I have a B&K Pro 10 that has both active and a buffered passive modes and sounds quite respectable. They are quite inexpensive on the used market and have two pairs of RCA preamp outputs plus one Balanced XLR pair. You could easily power two separate stereo amps with it and have your choice of passive or active modes.