When you need ASS
Use ASS when a side-loaded subtitle needs better positioning and style control: it carries concepts SRT lacks — canvas size, font styles, alignment. mpv, PotPlayer, VLC, and most players support it directly.
What the output looks like
The tool rebuilds a standard header: a 1920×1080 canvas, smart wrapping (WrapStyle 0), and a single Default style — Arial 54, white text with a black outline, bottom centered. Every cue uses this style.
Are styles preserved?
SRT has no style concept to begin with. And if your source is already ASS, converting rebuilds the default style and does not keep the original one — use a dedicated subtitle editor for restyling ASS. Timing and text are unaffected either way.