High Quality Universal Player??

It depends how resolving you want the player to be. The 103 is very nice for video, in fact the same as the 105. However, the 105 has a significantly better audio section and that is what the price reflects. The 105 sounds very nice; it ousted a Cambridge Audio 840C in my system. It was no small improvement. The Oppo sounds much better than the 840C. I have not heard the 851C, so I can't help there. I can tell you the video was much much better than the Marantz BD7003 Bluray player I had at the time. Very easy to see the improvement. I have not seen a Cambridge Audio CXU vs. Oppo 105D review, but would be interested.

Thanks.

Oppo says the sound quality difference is in the analog output - if I wind up feeding digital out into a digital pre-amp, it shouldn't matter.

I found a refurb 103 for $415 so I bought that.  I have 30 days to think about it, with shipping fees being around $40 if I send it back.

I'm sure there will be something groovier and much better as USB-C wipes out HDMI as an interface, as 18K video takes over, and so on.  For Disc players, I may just buy a new $500 model every 4 years, right?

I also have some 15 year Maggies I want to replace, maybe the Sonic Frontiers pre-amp I use and maybe even my Sunfire amp.  Not to mention the plasma TV, sports car parts, wine and etc.

I've had Universal Players through the years from Marantz, Denon, Oppo, and NAD.
  My advice would be to have a really good DAC for CD.  There are at least 2 DACs that have HDMI inputs which you could use with a BD player for SACD and Blu Ray (NAD and Bryston ), or failing that I would probably go with the Oppo 105.  Marantz players and amps tend to roll off the top end.
  If you were to tell us budget it would be easier to guide you

I have both the Oppo BDP-103 and the BDP-105D and have used both in the same system.  Substituting the 105D for the 103 was a definite improvement in sound quality to my ears.  They do use different DACs. The 105D uses the ESS Sabre32 32-bit DAC (ES9018), the BDP-103 uses a 24-bit Cirrus Logic DAC (CS4382A).  My Oppos, by the way, are used in systems with Maggies (1.7i or 3.7i), if that has any import for the OP.

LarryRS

I have owned a 105 for about the last 4 years now and I gotta say that it has performed very well. I recently performed an upgrade to the a/v portion of my system (minus the 105) and I was forced to use the 105 as an HDMI Switch. It performed brilliantly and note that the phone app makes it easy to operate all functions with your smartphone to boot. All of the streaming functions have also worked well too. My only complaint is that the transport mechanism doesn't always seat properly back into the unit when closing.