which speakers for low watt power amp?

Other than some really extreme designs and extreme applications (very large room, ear-bleed level requirement), a 75 watt amp should work with almost any speaker. I've heard notoriously hard to drive Magnepan 3.6 driven quite adequately with less than that amount of power. I've only heard the MBL speakers attached to much larger amps, but, I bet they would be more than listenable with smaller amps.

I don't think you are seriously constrained in your choice of speaker with that much power on tap. Like anything else, there will be synergy issues concerning specific combinations of gear, and that, more than power per se, will be important.

I like to listen to people singing, not that much into musical.

Couple of quick questions:

Do you have a price range you would like to be in?

What size room will the system be in?

Do you prefer floorstander or bookshelf speakers?

Taylor
www.goldprintaudio.com

I would probably avoid Martin Logan and any extremely power hungry speaker, but that's not really a low power amp.

Sonus Fabers can be beautiful with voices. They are also well known for having synergy with many mid-powered tube amps. Depending on your desire for bass...or 'only' voices...as well as your budget...the Guarneris are amazing and SOTA in the mids. I know them well having spent many years enjoying them, and you can speak with DaveyF about them, as he owns them. Hope that is helpful. One man's opinion.