Do I need a preamp/processor?

Erik's suggesting of combining an Oppo 103/105/203/205 with a Parsound P7 is an excellent one.  There are also looking at a really nice HT Processor.  It all depends on your budget.  Can you give us an idea of what you're able or willing to spend here?

Also, when playing movies, one of the critical elements is a center channel.  The center channel combined with left/right would significantly increase the clarity and impact of vocal dialogue and sound from the movie.  In movies, the center channel is used 90% of the time, with left/right being supporting speakers.  It increases the ambience of the movie experience.

I would think about adding a third LS50 speaker for center channel purposes and combine it with a Red Dragon M500 single channel amp, in addition to the Oppo/Parasound or an HT Processor selection.

The audio coming out of the TV via toslink is either going to be 2-channel stereo or multi-channel Dolby Digital (which can only be handled by an HT Processor).

I would not get wireless speakers at all because you will be sacrificing sound quality through the wireless analog-to-digital-to-analog process as well as the RF transfer medium.  If you did not want to buy another amp for center channel, you could get a "powered" KEF LS50W model.

I would connect the Sonos to the HT Processor using the digital coax output.  Then connect the analog output of the HT Processor to the left/right Dragon amps.  The HT Processor would handle all DAC and preamp duties, including toslink from the TV.

If audio quality is your primary concern, I would go with the 105 or 105D.  The 105D includes the Darbee video processing, which does help sharpen the image somewhat, as long as you do not overdo the Darbee setting.  I have my set at about 35%.  If you crank it too high, the image becomes un-natural.  The Darbee helps a little bit with HD, but it does more improvement with SD.

If 4K was a priority, obviously get the 203.  Then get a linear power supply upgrade, such as from these sources:

http://www.oppomod.com/

https://www.clonesaudio.com/accessories-1

Linear Power Supply is a significant upgrade to both audio quality and video quality.  The 103/203 series uses only a switching power supply (bad).  The 105/205 series uses switching power supply for digital board and then a linear power supply for audio boards.

105 stock vs 203 with linear power supply -- I'm not sure which one would win out here.  Getting rid of the switching power supply in the 203 will significantly help clean up and improve the audio.  Be aware that the 203/205 models do not include the streaming functionality (Netflix, Pandora, etc.).  The 203/205 also do not include Darbee.

It appears that the new 203/205 uses less power on the digital board because the amount of capacitance on the switching power supply is about 3/5 that of the 103/105 series.  It also uses an 8 pin internal power connector instead of a 15-pin (for digital board).

Actually, upgrading the switching power supply in any of the models will significantly improve things in any event.  If you got the 105, the linear power supply could be a future upgrade.

@blindjim - I see that you are really pushing the idea of a AVR Receiver. I don’t think this is really in autre’s best interests as he already has a Red Dragon S500 amp. If he is wanting to improve the sound, I would suggest a dedicated HT Processor instead of an AVR. Sure, the AVR is a great band-for-the-buck one-size-fits-all solution, but it is a compromise when compared to separates and also the OP here is not in that situation. The money spend on a receiver could be better spent towards an HT Processor that would yield better results for his amplifiers (better audio stages, better power supply, XLR outputs, etc.).

I am trying to respond to the OPs exact questions instead of going into an entirely different direction. I do agree that the Oppo players are a good solution, but if you look way back to my first post, I recommend an Oppo player PLUS a Parasound P7 preamp (multi-channel preamp). The Oppo by itself can be used to drive an amp directly, but the sound will be somewhat on the dry side and the Oppo does not exactly have the output gain that a preamp will have.

So, for autre’s recommendation, I would either say a nice HT Processor or an Oppo + Parasound P7. In either case, he has the ability to grow with adding a center channel speaker/amp if he wants to.

@autre - with regards to Oppo 105 vs 203. I would say that the 105 would have better sound because of linear power supply and fully balanced left/right outputs. That being said, if you get the 203 and upgrade it with a linear power supply (i.e. OPPOMOD), it may be VERY close to the 105 sound quality and has the ability to support 4K modes. However, keep in mind that the 203 does not support streaming services directly (such as Spotify, Pandora, Netflix, etc.)