Components, especially amps and speakers should be matched by how well they perform together and not by price tags. Your Tannoys are 8 Ohm, 90 db speakers so they won't require a ton of power to drive them - just good clean power with high current. If you tell us what Rotel power amp you have, you may find you have all you need right now.
Also, a lot of what you are seeking - depth, imaging, soundstage, etc. comes from the preamp and your Audio Illusions is a pretty good one but its starting to get long in the tooth. I would make sure its still operating at factory spec.