Are there apps/methods that allow for the sound to be forwarded to the smartphone?
So if I would watch a YouTube video on the PC, I could also hear the sound via the smartphone.
A cheaper option is SoundWire "Free version - Market Link" the free version will speak every 45 mins (just a nag) the paid version is under USD 4, link to it inside the same market link. Logically try the free version first. Sadly its PC only, not sure why as as far as i can see its a lite VNC app, sending only the audio and not keystrokes or anything else.
Honestly i find it extremely surprising that no one has made a Bluetooth headset, or similar profile for a phone. It would be very useful also for HTPCs as a kind of cheap (but very good quality) wireless headphones.