I'm now looking at a 2nd order with a resistor going to ground between two capacitors. What are your thoughts on that? I would also be lowering the cutoff frequency.
No, the free ride you get with the first order filter comes to an end when you try and cascade another stage because of insertion loss over the passband. You get away with it in a first order because the insertion loss is quite reasonable, yet the tradeoff is a weak slope of only 6dB.
The second stage of the filter would have a set of components in approximately a ten fold of the first, so the capacitor would be ~0.068uf and the resistor would be ~100K. This means that at the cutoff frequency, the capacitive reactance of the second stage would be about 100K. Since the input impedance of the amplifier is only 10K, you can see that over the small passband we're using, the loss would be overwhelming. Just not usable.
This is where you see the beauty of an active stage. No impedance concerns, no loss concerns, and slopes of any order you desire. But then, an active filter requires a power supply, PC boards, some knowledge of electronics, etc, etc. .....
brucek