Tannoy's are nice speakers.

Nearfields are designed for specific intent. Do you use those speakers with that amp for other things too? Nearfields should be set up a certain way (ear level, even distance etc)..

The good thing about powered monitors is you know everything was matched during design; speaker, amp and crossovers. It can make a difference.
How much?? Can't say without the dreaded comparison you mentioned.

I do not work here, but the benefits are still awesome
Make your sound your own!