[sdiy] More Passive filter stuff

[Haible Juergen]

More questions:

Are there passive filter topologies that are more tolerant to impedance
mismatch
than others ?  I'm aware that passive filters require a certain load
impedance
for their nominal filter response. Is there something like a tradeoff of
"mismatch
tolerance" and filter order for a certain required steepness, or is
impedance mismatch
a knockout factor from the start ?

Any good book recommendations on that topic ?

Thanks,

JH.