[morzh]

The line filter (X+Y caps) onlyh helps with what comes via the outlet itself and the parameters of the filter do not reaaly attenuate any audio frequency much, they are for radio frequencies or hi-frequency switching noise etc.

Also simple 60Hz hum has no way of getting through antenna. I think it gets in when a field created by 60Hz source (whatever it may be) is strong enough and oriented in a certyain way towards the audio circuits or detectors. Let's put it this way - if touching a grid of a tube results in hum, this is the suceptible circuit. So maybe just reorienting the radio or moving it away could help.