If you are using Google Chrome and you are unable to select HiFi as the music streaming quality.
You can go to chrome://plugins
Under the option "enable/disable native client" select always allow
You can also check to make sure that the NaCL plugin is enabled here chrome://nacl/, then you should see the following.
OS Mac OS X
NaCl plugin /Applications/Google Chrome.app/Contents/Versions/41.0.2272.101/Google Chrome Framework.framework/Internet Plug-Ins/internal-nacl-plugin
Portable Native Client (PNaCl) Enabled
PNaCl translator path /Users/username/Library/Application Support/Google/Chrome/pnacl/0.1.0.14206/_platform_specific/x86_64
PNaCl translator version 0.1.0.14185
Native Client (non-portable, outside web store) Disabled