Late to the party but fashionably late.
I worked for Harman International a long time ago and they, through JBL speakers, did a test as to how much power was needed to reproduce a solo grand piano at Carnegie Hall at concert volume sitting in the 10th row center. State of the art equipment all down the line from mics to amps to obviously JBL Pro speakers so you know the efficiency was around 98db w/m. The number will astound you.
400 WPC
So imagine a whole orchestra.
While I would say that the most expensive purchase should be the speakers, number two has to be the amp. You can never have too much clean power. Now I'm a "wire is wire" kinda guy that believes in ABX testing and the results it produces - some aren't. Spend your money on the things you can hear and not if the preamp has .001% or .002% distortion. Tubes produce distortion and for some reason it is of a kind that the ear-brain combination doesn't mind or even likes. Is it accurate? Not compared to solid state. Does it sound good? Yes it can. The trick is to find something that fits your ideal of the best of both. I'm a solid state guy although I did have tubes 40 years ago. The quest for power and in some cases volume took me in that direction since I've almost always had speakers that could handle it. Just because your speakers aren't rated for the total amount of power your amp can put out is not a bad thing. Having that 3,4,5 or even 6db or more of headroom won't hurt. I've seen 50 watt rms rated speakers take 1KW pulses with no ill effects.
Buying classic equipment (I mean used) will certainly save some money unless you start chasing collector pieces. Older Bryston, Classe, Threshold, McIntosh all will perform well for as long as you want to keep them. Get speakers that will match the area they are going in. Decide if you want near or far field or want a home theater system. Smaller monitor speakers can do wonders hooked up with a good sub if you lack the room for floor standing towers. Not too small because you'll hear the sub location if it is crossed over at anything higher than 100hz.
Personally, I would never buy another set of speakers if it didn't have at least a ribbon tweeter at the minimum - preferably a ribbon mid too. You WILL hear differently than I so the same may not hold true. Doc was right though. If you are starting from scratch spend at least the next 6 months listening to speakers that fit your budget, size and needs. A good store will let you take them home for a bit and when you are listening take notes. What did you like about how speaker X played song Y. How was it different than speaker Q or R? What didn't you like? What speaker had better low bass, mid bass, vocals, wind instruments, strings, distorted guitar. You need to listen to a wide sample that may take you out of your comfort zone for music. Demoing speakers was how I got hooked on Organ music for example.
If you want you can PM me if you have any questions.
I'll keep it short as I'm on my phone. I'm in the Class D amp camp and loving it. I have a Peachtree nova 125 with a built in tube preamp. The Peachtree is powering my Carbon 7 by Fritz. I also have a Bowers and Wilkins ASW 610 sub. As you can see I went the 2.1 route with no regrets.
