Where do I start-amp or speakers ?

You pick the speakers than match the amp to them.Enjoy!!

I would recommend to start with the source.  Though Speakers very in sound reproduction, dept, sound field, presents, bass, clarity and maximum power you will not have great sound without the clean Pre-amp / Power Amp.  It sounds like you had very high end audio to start and I question why you sold it?  The powerful Amp you had would work most anywhere.  The speakers I can see because of ergonomics alone.  
If it were me and you have the money invest I think you already know the market you will be in for cost and quality for the electronics. 
 Not Sure if you are thinking about space taken up by big amps so may I suggest an Anthem Integrated.  There are many good ones out there to try out and they do not require a ton of room. A Blue Vault would be a good streamer and hard drive for playing.    The speakers are a matter of what you like to hear in the music and I would ask the dealer (With promise not to cash the check for a few days) let you audition the speakers in you final room location with the furniture, decorations, (Drapes and such if there)  and all you will have in the room.  The room acoustics will be a factor and you want Speakers forgiving enough you are going to be happy with.  I like to audition in the room at my place because it will be with your equipment.  Hear it first at the dealer but do not give final payment until you know they perform in your setting.  My 2 cents worth.   

We all agree everything is important 😉 I will certainly agree that the source is critical as everything else in the chain is dependent on it to sound its best.  Great up front gear coupled with a good speaker will yield wonderful results every time. Poor upfront gear will always limit a tremendous speaker. In the end get it all right 😊. Yeah, that’s it. 

I have a rich friend, a very rich friend , who started with a ten K system and over a years time in about 20K increments moved to a 100 K system .
The 1K speakers he started were never changed because he liked how they looked .
They had no problem showing what was what all the way up from Odyssey to Lamm .

How many of us have actually started assembling a system from absolute zero--without a single component carried over, gifted, inherited, or whatever?  In that rare case I'm going to say speakers, because (a) room size, speaker size and appearance, are much more variable and need more accommodation than electronic component size (17" anyone), and (b) all other things being equal*, variation in speakers makes a more immediate impact on overall size. (In a reasonably balanced system, where $$ are equitably spread over the different components.)