HELP SUGGESTIONS FOR A BETTER SOUND

I like your gear, not the speakers, so maybe try auditioning some different brands to see if anything strikes your fancy after all those years.

i've owned the solos and still own the studios. the solos are a great speaker, but have a certain attribute, which is they're power hungry and really open up at higher volumes--they're not really optimal for polite, low-level listening. i agree with the general consensus--changing your interconnects won't make an audible difference. changing your preamp or power amp will alter things, but probably won't change the fundamental character of the speakers. if you want to hear a significant difference, you'd probably need to change speakers. (i haven't heard the aads, but would conjecture that they share much of the signature of the solos, so i'd look at something else).

I had the exact same ic you are getting. Imo, they are impressive sounding albeit slightly colored. Images are nicely illuminated but at most times seem larger than life with noticable boost to their midrange and in particular--bass. Unless you fancy or specifically looking for these characteristics in tuning your system, I would pick another--one that's more neutrally balanced. Good luck!

Room treatments.

I seriously doubt that changing interconnects or speaker cables will make much of an improvement

I seriously doubt that changing cabling would NOT make a significant difference!
Hi Jim: THE way to build a rig is to first settle on speakers that you enjoy, which you have now, and then optimize around them. The way in which you descrbe your sonic signature you are almost there right now. Yes absolutely do experiment with tweaks and cabling by all means. Shelving, footers, rack, roomtuning, interconnects, speaker cables, AC cords, AC line conditioning, dedicated AC circuit. There is SO much that you can do with what you already have. Cabling will absolutely improve your stage & image, and the Synergistics are a very good approach in my experience. I have a LOT of Synergistics in my rig.
I have to wonder about the Nordost though. I fooled around with those but they were thin and detailed in my rig. Still you never know: synergy is key to all things audio and the only way to find out what works well for your rig, your room, and your preferred sonic signature is to experiment. The cable that works great for my rig may be terrible for you, & vice versa, you just never know.
However if you want to experiment with speaker cabling I highly recommend trying MIT. Not their cheapest and not their best, just go with what's good-yet-affordable for you. I love the MH750 Magnum series although it's now dated.
Bear in mind that some cabling takes quite a long time to settle in, so don't think your first impressions are necessarily valid and give them some time before you change to something else yet again. 30 days is a good starting point in that regard. Have fun!