I'd have thought what mattered is the low pass filter break point formed by the output stage/input stage [resistive] impedance and the cables [capcitance] impedance (plus any input capacitance of the power amp). Even if the output stage impedance = input stage impedance as long as the LPF break point is high enough should be OK.
Hence a passive pre with a 100K pot has a max ouput impedance of 25K [pot in the middle]. If this drives a cable of say 100pF/m - gives a -3dB point of 64kHz for a 1m cable, but 6kHz for a 10m cable. [You probably want much less than -3dB at 20-30K] So 1K should be fine as long as the cable capacitance is low enough - i.e. it is a relatively short enough. So if the target LPF break point is -0.1dB at 20kHz, it is -3dB at ~130kHz, which would equate to ~12m for my theoretical 100pF/m cable if I have done the maths right(!) [input impedance >>1K] -- Triode ------------------------------------------------------------------------ Triode's Profile: http://forums.slimdevices.com/member.php?userid=17 View this thread: http://forums.slimdevices.com/showthread.php?t=27445 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
