Sound quality impact - preamp vs power amp?

 I am in agreement with @tvad.  I would like to point out that it’s easier to get a flat impedance curve with lower impedance speakers, and  that due to that lower impedance those speakers will most likely (speakers like tvad’s Soundlabs excepted) be less sensitive.

The amplifier is far more important than the preamp even if it has a phono stage. Amplifiers and how they are matched to the loudspeakers can make or break a system. See what happens when you put an 8 watt SET amp with Wilson's. Some speakers require a lot of power. Without it they are lifeless. Makes no difference what preamp you are using. 

Sounds like a hypothetical question to induce responses. If the OP was serious, he'd simply consider an integrated amplifier within his remaining budget. Would you put an entry-level cartridge on a high-end turntable? Which is more important when all things are important? 

Speaker and amp tech may not change so often as the preamp/streamer/DAC   So my view is nail those down first.  Make sure you can return whatever you get. Happy hunting. 

This is getting old both are very important.HELLO!!