What to add or change for my system?

Jumping in here. Like others have said, you have some excellent equipment selected here. Since you are fairly new to this game, I would also suggest (like others) to listen to this system for several months and get used to the sound. I’ve been in this game for about 17 years and sometimes I can immediately determine when something isn’t working, but sometimes it may still take me a couple months to realize something is wrong or there is some characteristic of my system that is bothering me. That being said, I would suggest making tweaks to your system instead of doing major upgrades. Some tweaks can actually make significant impacts to your system.

Speaker cable risers - I’m not entirely convinced that speaker cable risers really work....but, if you want speaker cable risers, I would think that Styrofoam is not a good material to use. Styrofoam can be susceptible to static electricity and cause magnetic fields. It would be better to use a non-magnetic material (such as wood) to build your speaker cable risers. I’m sure you could fabricate some cheap risers made from wood components (even just tying a few wood sticks together with string as a riser).

Interconnects - I see that you switched to Avanti Audio interconnects, which use a 26awg conductor. While there is much controversy in the industry as to the best awg for an interconnect, I have found that smaller wire gauges will give a more closed-in sound. I have tested this (using an Vovox 26awg solid-core audiophile interconnect). What happens is that there is somewhat higher resistance with smaller gauges. I have found that larger gauges will let the music out (in a sense larger awg will allow the music to "breath"). More powerful bass. Instruments hit with more authority. Your previous interconnect (Kimber Timbre) uses a varistrand setup that has a much larger 19awg conductor. If you still have these, I would suggest putting them in and see how they sound. Because you have such a strong solid-state system, I would stay with copper here.

Speaker Wire - I have use silver cable in the past. It has its own sonic signature. Some people love it, some don’t. I have evolved to where it is not my personal taste. Silver is fast and will tend to push the upper mids/highs. Bass can be light/weak. Silver can be good when paired with slow/warm equipment like tube or McIntosh (definitely not Plinious). Once again, this is all personal taste and I recommend you listen for a several months before making a decision on silver.

Burn in - both equipment and cables require some amount of burn-in before sounding good. Usually, the recommended time is around 100 hours of constant use. Some elements (such as rhodium plating and some types of electrolytic capacitors) require 200+ hours. I know for a fact that the Oppo 105 needs well over 200-250 hours of burn in before it settles down and sounds best.

Fuses - the choice of fuse can drastically change the sonics in your system (believe it or not). There are so many different opinions here. Personally, I found Furutech Rhodium to be the absolutely best (but burn in for 200+ hours!). I will say that rhodium plated elements are very transparent and revealing, so much that it could reveal problems in other areas of the system and you may end up replacing all fuses/connectors with rhodium plated Furutech (like I did). However, the end result is absolutely outstanding. A much more forgiving fuse is Isoclean, but some may find it too warm sounding. Hi-Fi Tuning Supreme are silver and are fast/detailed, but push mids/highs in a way that’s artificial (in my opinion). Synergistic SR20 is very fast and clean, but it was so clean that I lost emotional connection with the music. Synergistic RED is the least offensive fuse I have found. The RED will sound okay in any system, but not extraordinary. I found the resolution lacking, but it didn’t sound bad. I have not tested SR BLACK. The cost for me too much to try this over the Furutech.

Power cords - I can go on a very long discussion on this subject because I have spent a LOT of R&D in the last couple years on this, but I think you have enough to work with for now.

Finally, if you do make a change in your system, please make sure you burn in the device (if it is new). Then listen to it for several week (or a couple months) to get an idea of what you are hearing. Then make a decision on whether or not you are keeping it.

oh, forgot

Room treatment - be very careful about acoustic treatments. It can be really easy to over-damp a room and then the sound becomes dead. If you have hard-wood floors, then put as much broadband acoustic panels up as you can (in corners especially). Contact GIK for advice. Their panels are excellent for the price.

If you have a fully carpeted floor and/or plush furniture, be very careful on how many broadband panels you put up. I would almost suggest using membrane type panels, like the GIK FlexRange Limiter. Alternatively, use Owens Corning 703 FRK panels. The "FRK" panels have a foil front that does much the same as membrane -- it mostly reflect mids/highs instead of absorbing them and keeps the room live and exciting sounding.

Just re-read this thread.  I see that you got SR BLACK fuses.  One of these days, I will probably have try one, but my testing with rhodium plating and Furutech components has been so successful, it may be hard for me to change.  Though, like I said, rhodium is a double-edged sword.

For the Oppo, google for the "oppomod" website and go buy a linear power supply for the 105.  It's a bolt-in replacement (no soldering necessary).  And you can easily upgrade the fuse in this linear power supply.  Even if you are just using the Oppo as a digital transport, a better power supply for the digital section is still a benefit.