because i have owned some of the speaker package you talk about and i heard it on the end of a yamaha A5 amp! So in part experience.
The biggest concern you have with an amp speaker match is to get ENOUGH power, not too much. I havent actually heard of anyone sensible damaging speakers by using too big an amp. I have certainly tried some exotic configs.... 200W into a 50W rated speaker and have done no harm (of course you can damage it if you go insanely loud, but this will be true of most any speakers).Although the stated sony power seems above the speaker ratings, it is almost standard across the amp area that the ratings are bloated by driving only a single channel at a time and potentially with large distortion. So basically your real world power is very unlikely to be even approaching 100W.
The most appropriate way (in my view) of assessing compatibility from specs is looking at the speaker sensitivity (which effectively is a guide to how loud it can go with a given power) and the speaker impedence (which is the speakers resistance basically, how hard the amp has to push it to make it go if you like). Together those give a guide as to how hard the speaker is going to be to drive. Impedence of 8 is preferable with a budgetish amp and a sensitivity of high 80's is typical. Amp wise, this one is tougher, i will generalise in terms of its type and cost. With a £300 amp, I would say it should only be given an easy speaker load. Say £100 and i would allow use of a mediumish load but it would take a big processor power amp setup costing many thousands until i would want to use tough speakers. So basically, its all about making educated guesses.
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