DAC or pream

I am currently running an A-21 Parasound amp to Magnepan. 7's. I stream exclusively now with Amazon. I am currently using an Emotiva PT-100 for my DAC and remote. I looked at a P6 but dont need the phone or other preamp features. 

Will I improve dramatically if I switch and what would you reccomend? I need remote volume control and USB input.
Hello. I would guess that the Emotiva PT-100 is your weak link. That's a lot of features to have in one box for only $329. Preamp, DAC, phono amp, tuner, headphone amp and even Bluetooth. I would bet the Parasound P6 would be a good step up. If you want to have the one box solution.
Oh and FYI your Emotiva is a preamp so yes you will still need preamp capabilities. Now some DAC's have built in volume controls so they can act as a "digital" only preamp but don't usually have analog switching. But you said you don't need that anyway so that could be a possibility for you. However quite often a dedicated preamp will sound better but that is a topic for another day,