I agree with all that dan delahuntly says but I believe further comments may be useful.
Power-Peak instantanous power is loved by manufacturs and retailers alike. A amplifer that can maintain 100 watts for 10 seconds may disolve at 20 seconds. RMS (root mean squared) power is no better and sustained power for a long or short peroid can produce the same result. A genuine !00 watt amplifer amplifer system is ridiculous if you want to stay in the same room with it at full blast
Distortion- Another great retailing trick. The amp that has a genuine .5% distortion at .25 watt hs 5% at 10 watts when you are listening to it.
Finally- A 20 year old amp. has two handfulls of condensers and resistors that are outside of origonal design charactisics. Does that mean you can not buy a 20 year old ,masterpiece at much reduced cost and be satisfied. No just watch it. .