Agreed that scratch repair on finished wood is a learned process with many technique approaches based on the wood, the finishing process, the quality of the original finish, etc. For me, if abrasives are out. If abrasives are used then the whole speaker cabinet should be refinished for perfect results (sheen matches) -- which exposes whole issue of finishing product compatibility with the original finish on the cabinet, removing drivers, dust free workshop, application techniques....
I think Abstract7 means Old English products, which come in several color choices.... They work well to hide the appearance of a scratch, but will not be perfect like a professional scratch removal would be - but a heck of a lot less expensive.
Personally, with the furniture I build, sandpaper never touches the piece -- IMO sandpaper is an evil workaround to proper woodworking craftsmanship. I use finish scraper planes and steel wool for the finish (not applicable for venier, such as most speakers are finished). There is no way that sand can sever the grain of wood like a plane knife can shave it... Off the subject, but my $0.02.
My recommendation still stands -- appropriately colored filler sticks / products or Old English colored oils. Other stain products may accomplish the same effect. Maybe an Woodcrafters or Rockler store can recommend other products and techniques. They forsure have books on the subject...