hifi engine

Mitsubishi DA-R15 receiver and Bose 901 and Infinity Outrigger jr

First I do not feel the Mitsubishi and Bose are properly working but can not for the life of me figure it out. Second, can the receiver handle also the Infinity speakers? Thanks for any help. The Bose amp when manipulating the midrange or base controls seem to have no effect. The only affect I can get to see that something is changed is to toggle back and forth between off and tuner on the record selector switch of the receiver. Third, is there a device that allows choice of inputs to speakers just backwards from choice of speakers on a receiver. In other words like a wall switch to switch from speaker a to b only switch input to speakers (outdoor Infinity) from receiver a or receiver b. Thanks in advance for any help on this.