Fifth order passive filter - band pass

[FvM]

I thought that an op-amp in a buffer configuration can be the solution but when I use it the signal is drastically lowered.

Would prefer a schematic together with a measurement that shows where "the signal is drastically lowered". I already mentioned the problem of OP drive capability (maximum output current). I think however that 50 ohm impedance is far from optimum for a 30 to 100 kHz filter.