Jim Audiomisc did reply but maybe didn't address that question.
Generally speaking you can't say for sure that a mains RF filter will be benign at lower frequencies. It will always present some inductance at all frequencies, in series with the inductance of the mains itself. Enough series inductance in the mains will impede the charging of the reservoir capacitor in a linear power supply. So the filter (+mains) has to be good enough. So the question is "is it good enough?"
The UK mains at a domestic socket typically has, AIUI, about 750 microhenry inductance. The common mode choke in a 15 A mains filter may add about 50 microhenries differential mode inductance to that (but DM inductance is not always specified for mains CM chokes so I am not entirely sure of the figure).
I have also not done a real worst-case calculation (for a big power amplifier) but if kit is designed to cope with the normal mains then adding a good high-current RF filter looks OK. But a smaller mains filter might add too much impedance. I have no feel how small is too small.
In general terms any filter - or length of cable - will add some series inductance, series resistance, and shunt capacitance. To go further someone would need to determine the values. But note that your mains power connection is essentially a series of lumped items (sockets, ring connections, etc) linked to/by a network of transmission lines and other complicated items - e.g. light fittings that act as unbalanced stubs.
So if you are worried about the effects of an RFI filter or the cable from the amp to your wall socket because of the impedances and/or RF involved, all these items have to come to the party!
Where did you get the value you quote for a mains socket inductance? And what would be the comparison capacitance and effective transmission line impedance? I suspect these vary but the ranges of values are known given that manufactures design and flog the obnoxious 'powerline' data home feeds. But I've not found a reliable set of measurements for these values which I would expect to vary over quite a wide range from case to case.
The CM/DM ratio of a CM choke should be reasonably high because of the topology. But again, this will depend on the design details. How they compare with the inductance of a mains cable is something else I'd be interested to know. The general effect can be seen from Fig 2 on
http://www.audiomisc.co.uk/mains/filters2.html
To calculate it, you'd need to know the sizes and positions of the wires and ferrite to be able to do the required integrals - or just measure one.
You can, of course, fit RF filters that just use shunt caps/snubbers, not inductors, and they won't add much series inductance. But you are then relying on the inductance and resistance of the mains cable for them to work.
In practical terms the only point I can add is that my experience is that when I've encountered mains RF a filter works but a change of mains cable didn't.