Some av receivers are good for hi fi. for example, an Arcam AVR500 is very good at reproducing music. it's also fairly expensive...
As has been stated, spending £350 on two channels of amplification is going to get you better sound per channel than spending the same amount on eight channels. Decide on your budget and your priorities. If you want surround sound, concentrate on an amp that does just that. If you want two channel music get a good stereo amp. If you want both, and your budget is limited, look at getting an AV amp where their are pre-outs for the front pair and send these to a stereo amp, so that your two channel music benefits. Also look at older models and even secondhand amps - there are some bargains to be had, especially for older stereo receivers. For example, a secondhand Arcam A85 (like mine) can be had for around £250. It cost £1000 new and is still a cracking amp.