chassis-mounted filter or IEC plug filter

I'm thinking of getting one. I might also get an ordinary chassis-mounted filter as I already bought an IEC plug. I'm not sure but would a chassis-mounted filter do the same job as an IEC plug filter.

If I do use a chassis-mounted filter, is the metal casing connected to the mains ground?

Also, how do I select one based on amperage? It comes in 2A, 4A and 6A. I'm thinking of getting the 6A.

Also, I've seen in catalog where a chassis-mounted filter has an earth line choke. what is it?

Any ideas/suggestions are greatly appreciated.

Thanks :)
 
it's only for a headphone amp. In that case, 1A maybe be enough. right? Also, are IEC plug filters and chassis-mounted filters the same? I would really like to get the chassis-mounted if possible as I already have an IEC plug.

Thanks

ps. I don't need links to manufacturers as I already have one in mind and it may not be available to Australia. I just need to decide on what type to buy. Thanks again. :)