Additive invariants of finite dimensional algebras of finite global dimension

Let k be a perfect field and A a finite dimensional k-algebra of finite global dimension (e.g. the path algebra of a finite quiver without oriented cycles). Making use of the recent theory of noncommutative motives, we prove that the value of every additive invariant at A only depends on the number of simple modules. Examples of additive invariants include algebraic K-theory, cyclic homology (and all its variants), topological Hochschild homology, etc. Along the way we establish two results of general interest. The first one concerns the compatibility between bilinear pairings and Galois actions on the Grothendieck group of every proper dg category. The second one is a transfer result in the setting of noncommutative motives.