Current RAF practice, even on Elementary training aeroplanes - Grob Tutors and the like, is to have radios on pre-start, local procedures will dictate whether they are also checked pre-start. Does mean you have someone to squeel to in the unlikely event of a fire on startup, although that's obviously only a factor if at an airfield with fire cover!
However, as the avionics fitted are relatively new and shiney, they may, for all I know, have built in over- and under-voltage protection, that may be lacking in older radios. That's based on absolutely knowledge of avionics design, a pure unadulterated guess!