Amp first approach to build a system. Anyone did it ?

I’ve always considered the source and speakers first and move on from there.

While I have not done this myself, I might be tempted given the amp I currently own (a clone/re-build of a Western Electric 133A amp).  The other amps I have are also low-powered amps that require fairly high efficiency speakers.  Really good amps make a lot of difference, so it might make sense to at least look primarily at that type of speaker, that is, if I were in the market.  Right now, I am more into upgrading my existing speaker.

It would be best if you tell us the specific model number of the amp you will keep and use, then it is more a question of avoiding a poor speaker choice.

I had a pair of vintage tube mono blocks 30wpc, 4,8,16 ohm taps, big transformers. They were the start, period, then compatible speakers, and a tube preamp.

You are going SS, no problem, but we need to know the amp's specifics to give you good/avoid advice, not specific speaker models, just what to avoid technically.

I own 3 systems, a living room one, a smaller dedicated room one, and one I setup outside during summer months. All have evolved, sometime having speakers looking for an amp, sometimes having an amp and looking for speakers. Sources have also changed. 

More than one way to accomplish a satisfying result.

Think J Giles said it best. “First I look at the purse.”