There are few good options beyond getting a dedicated amp and speakers
High quality powered speakers
http://www.audioengineusa.com/Slim Devices Boom:
http://www.slimdevices.com/pi_boom.htmlIt's really about the question of whether you want actual all-house audio distribution with low quality sound (which is totally fine if all you want is background music), or high quality audio managed via Vera delivered to where you actually need it.
Real world cost of Slim stuff is much lower because it's designed to work with existing equimpment - your home stereo/HT, mini systems in bedrooms....
Coupled with Audioengine speakers it can provider very good background music for non critical listening, and this is all over Wi-Fi, no wires, move it as you want.
Their Boom is all in one client with very good sound and unlimited mobility in WiFi range.
SlimServer can run on virtually any computer, any OS, and on some small boxes. It can stream any non-DRMed music with no loss in quality. Tons of plugins exist, and it's as hackable as Vera itself.
See, it's about a different perspective on audio comparing with classic all-house audio distribution systems.