those all work but in the short run wouldn't it be a lot easier for BBC (or DTV or whatever the company is) to animate the logos, rather than make evryone who is a little bit concerned have to turn down brightness/contrast to listen to the radio stations and then back up when they switch to TV?
if channel4 broadcast their station at half the brightness of other stations you'd soon get tired of in/decreasing your tv controls everytime you wanted to watch a bit of Frasier...you'd get in touch with them and tell them to sort their life out.
at the end of the day if they were to animate the logos it wouldn't detract from anyone elses enjoyment but it would improve a few other peoples.
just my two pence worth
as for routing my STB via an amplifier, i realise this is probably heresy on this forum, but i ain't got one

(an amp that is) which i think probably puts me in the same category as 99% of other people who will signup to freeview.