Created by CatsTuxedo on May 13 2014
For what minimal characterization Tirek received in his debut appearance, Caroli certainly brought a satisfactory amount of authority, menace and theatrics to the character and makes for one of the more memorable voice performances from the franchise's early days.
Comparitavely, Acheson's performance benefits from being much more faceted. For the first half of the two-parter, Tirek is a small and weak character that one would nevertheless not want to run into, and Acheson's quiet and wizened delivery compliments that aspect nicely. In the two-parter's second half, Tirek is much larger and more powerful, and Acheson modifies his voice accordingly by making it louder and stronger. Acheson's naturally low and rough sound goes with this change wonderfully as it gives the character a fittingly bigger sense of presence.
While both actors did well with their respective performances, I'm giving this one to Acheson.