Where do I start-amp or speakers ?

Amplifier speaker integration is only hard if your speakers have a hard to drive impedance curve, and if your amplifier has a high output impedance. Avoid those two problems and there is no real issue unless you are a hypochondriac.
If the budget is indeed 8K for a medium sized room, I would allocate most to the speakers: Harbeth SHL5+ are perfect for such a room, and they are easy to drive. Harbeth make some of the cleanest, musical and non fatiguing speakers on the market. They like a bit of power, so why not go for an affordable solid state pro audio amplifier like the 2x350 watt Yamaha P3500s? See here for a test that proves that it is perfectly suitable for domestic use: http://www.homecinema-fr.com/forum/amplificateurs-de-puissance-haute-fidelite/mesures-ampli-yamaha-p...
I recently bought the slightly weaker 2x250 watt P2500s for my son, and the sound quality is just perfect. The variable speed fan never comes on in domestic use. And as a pro audio unit it has balanced inputs for lower noise. Built like a tank.

Absolutely, it is all about the simple mathematics of relative error. There is litle point in worrying about 0.001% difference in distortion in the electronics if the speakers have 1% or more. The same is true or frequency response where electronics are usually perfect wthin 0.2 dB, but speakers may easily deviate from flat in even the mid frequencies by a few dB. It is simple high school maths. And for those who don't like science: you can hear it.