My shield TV remote has Infra red and you can use this to directly control an amplifier. But it only allows you to control by picking from a long list of manufacturers first. Which brand has the same volume control codes as the B50?
OK - I guess it is a stupid question - if there could be such overlap then stuff would never work properly. The main issue here is that the shield has no learning mode or other way to add IR settings of new devices.
I’m not sure, but you could check the IR code in the end of this page, and find a way to update into the Shield TV remote.