Just a bit to bright

Hello,
I've been listening to my entry level system for almost a year now and while overall I am happy with the sound quality, it sounds just a bit too bright at times. My components are an NAD 326BEE integrated amp, Onkyo C7030 CD player, Sonos Connect for streaming Spotify, and Speaker Design Works MiniStatements speakers.(DIY)
http://speakerdesignworks.com/MiniStatements.html

I have not noticed any significant difference between CDs or streaming music sources so I feel like if I wanted to find a sound that is not as bright, I need to consider changes at the integrated amplifier. Since I built my speakers and feel proud of them and their sound, at this point I'd like to try and find the sound I'm looking for with these speakers. I do understand, it is possible that someday.... they may become a component that needs to be changed.

So my thoughts are, try a different integrated amp, try a different amp and use the NAD as a preamp, find a preamp and use the NAD for an amp, or try a class d audio amp... claiming to have a warm tube like sound.

My question is do I just need to jump in and try one of the above?

Which component (not the speakers) would likely have the biggest impact on a system that is a bit too bright?

Any suggestions would be greatly appreciated.

Jeff