Quad 2905 vs 989

 Can anybody help me with the sound difference's between the 989 and the 2905's. How reliable are the 989's?? I have the option to buy 989's secondhand at a much cheaper price than the 2905's is there anything to look for when buying 989's secondhand. I have a Dac and want to play music from my Mac so I need an amp preamp and cables how much should I look to spend to get the best out of Quad's big boys. Many thanks for the help.