Seeking advice on how to improve my system

I would recommend working on your AC power. Once I got all my components and cables tweaked, I added balanced transformers and it made a great improvement to the system.
I also recommend dedicated AC outlets. One for your CDP and one for your amp. These will be worth while up-grades that will enhance any new component in the future.
Have fun.

Your system is fine as it is IF you like the sound it is presently making. If you are unhappy about the sound, what is causing it? Personally I think I would find the wires and CDP contribute to some excessive brightness but that is just a WAG.

One thing you might consider (if you haven't already) is set up your listening chair so it forms an equilateral triangle, or close to one. In a small(er) room you can get the speakers closer to the side walls by toeing them in so that the axis' of the speakers cross well in front of your chair. This will allow a wider soundstage and allow you to sit further from the speakers (Thiels really sound best at least 10 ft from the ears (my Thiels/my ears) because of the design of the drivers. The toe in will minimize side wall reflections, a must with Thiels also.

Next, assuming you did the above, bring you speakers out in the room a bit more, maintaining the triangle. This should improve your depth of image considerably. Mine were set at about 5' from the wall behind them 2.5' from the side walls, and the chair (ears) was 10 ft from the plane of the speakers.

I used this set up with Thiels 3.5's/ARC SP10II/Threshold SA3/BAT CDP/ and a Oracle TT w/Grace Cartridge. My room is 19.5x13.5x9.

Worth a try if you can do it. Just takes a few hours to see if your going in the right direction. If you are you can fine tune it further as time allows. Don't minimize the effect of the listening chair. A few inches can make a significant difference.

Hope you don't have those dreaded aesthetic problems.:-)

You have to determine what sonic characteristics you want to change. Then we can give you some advice as what to change. Do you want more dynamics, resolution, soundstaging, deeper bass etc, etc

If you're at the point where you're feeling vaguely dissatisfied with system performance, but aren't sure exactly why, I agree that power conditioning may be a good and likely place to start. But, before you accept coventional wisdom on it and start plunking down serious coin to get the gains you want, try this: go to the facebook page of Alan Maher Designs. You can't buy anything from him unless you friend him on facebook, but there's no other obligation. If you want the commercial, Alan makes a wide variety of gizmo's for systematically treating both system and home, but that's because he feels that one-box solutions necessarily fall down on treating RMI/EMI because they don't cover all the points of noise entry into the system - through home and system wiring, the components themselves, every appliance and power supply that's plugged into your home and even through the air. He offers some pointers on how his devices work at killing electrical noise, but don't bother coming to a full understanding before you try something of his because A) he is the only one that truly understands it and B) he doesn't have any patents on his gear so there's only so much he can openly divulge. Instead, just do this: look for a product he has called an "ION CBF". Ion as in the charged particle and "CBF" as in "circuit-breaker filter". This little dude tapes inside your circuit breaker box in about a 2-minute install (see his site for full instructions and Alan will answer any questions). Then you must wait 30 days - not 29 days, not 3 weeks, but 30 days. In the meantime you won't see what all the fuss is about - in fact (if you installed it right) your system performance will tend to go into the tank, but 30 days later your system's sound will be transformed - and in no small way either, just about everything will be better! I gaurantee it (everybody's system suffers from this kind of noise). Price?: $30, but I can promise you it will be the best 30 bucks you ever spent on your system. You'll likely be hooked on his products after that (I was), but the price of admission is as cheap as it gets for products that notably don't roll off frequency response or curtail dynamics as so many other kinds of power-conditioning products do. My advice is to do yourself a favor and give it a shot and see. Good luck.

Ivan you sound like a crazy nut who is trying to play head games with audiophiles lol.

Since you said you have a bug to upgrade I would say to try out some new wires. You could buy some used and you won't lose much if you dont like them you can just resale. Go for something in contrast to what you have now and see what you think.

If you wanted to do something big I personally would go for a top notch preamplifier. In my experience great preamps have rocked my world over any other upgrade. If you sprung for something like the CJ ART or ARC ref 3 I bet it would put a big smile on your face.