Over time I have accrued two pairs of older speakers by various yard sales or gifts from friends. One is a pair of Sony bookshelf speakers rated at 60w max power and 8 ohms impedance, and the other is a pair of Pioneer towers rated at 160w max power and the same impedance. I would like to drive all four at once using my PC as the audio source, if possible- what sort of amplifier should I get for this task, and how should I wire my speakers up (in case I get a 2-channel and need to connect all four at once, for instance?)