Preamp, Amp, Tone?

I have Sonos Port connected to my Preamp, which is connected to my) Amp, a Sub, and 2 speakers. System also has (finally bought) a nice turntable and CD player. Lately, I'm finding I use the Port as a streamer for majority of listening (I digitized most of my CD library). The sound is good, but lately I find I want to adjust the tone of the music, as previously my integrated amp did that. What component(s) should I consider (besides tube rolling which I've not yet tried) for adjusting tone? Should I consider another DAC? An equalizer of some kind? Forget about the Port? Any and all suggestions are welcome!