The sound system.  The head unit is a Sony ES-650 powered by a Sony XM-5046 four channel amp.  The front speakers in the Q-Forms are Polk DX-3055 five and a quarter inch with one inch tweeters.  The rear speakers are Polk 6x9 two way speakers.  I used a ten inch Polk sub woofer powered by a Premier GM-X632 amp.  Not the best system in the world, but not to shabby.