Benchmark Results: Audio/Video
iTunes is single-threaded, and is better-accelerated on the Phenom II X6 with Turbo CORE enabled.
The same applies to Lame.
MainConcept is optimized to take advantage of multiple cores, so it benefits more from Turbo Boost, which can kick in even if many cores are taxed.
Once again, we see the multi-threaded advantage in HandBrake, where AMD's processor easily hits its limits on all six cores, preventing Turbo CORE from kicking in.