you don't need a 300 watt amp, a 50-75 watt amp/receiver will be plenty. Just because a speaker can handle a high amount of wattage, it doesn't mean you need to buy one that powerful.
One of my receivers is 50 watts/channel and I used it with better speakers than your Sony for 8 years.
Are you planning to use your speakers just for two channel listening? CD's, MP3's etc or do you eventually plan them to be part of a home theater system?
It may make the difference between choosing a home theater receiver vs a stereo receiver.