The 751BD and the Oppo are similar because they are made in the very same factory. Good read at 6Moons.
"Nobody taking a glance at the back plate or a peek inside will need to be told that this deck is built in the same factory which manufactures for Oppo, one of the biggest specialists for multi-format players. Any Internet search eventually identifies the actual manufacturing plant as Winbase. The 751BD is actually a kind of premium version of the BDP-93EU which Oppo manufactures in China. According to Adam Shaw-Cotterill, head of marketing for Cambridge Audio, all their previous DVD players and one BD were manufactured there. Later CA bought from their Chinese partner certain projects which are made on a different production line because the British company specified certain changes to Oppo’s core platform. The most important of these is the large audio PCB. In the Oppo signal processing for all channels is handled by a single CS4382 chip without prior DSP. Cambridge runs individual Wolfson stereo chips for each output pair."
6moons audio reviews: Cambridge Audio 751BD
Also Oppo doesn’t make the platform it comes from Mediatek from which their universal players are based ( also Midiatek provides the decoding chip MT8530HEFG, the Mediatek MT8520 SOC . Mediatek, an o.e.m company that still happens to provide Cambridge Audio it's platform. Mediatek happens to reside in Taiwan. So it appears like a lot of parts come from Mediatek and no doubt Oppo and Cambridge change a few things and then these players are assembled in China.
I've heard both players side by side and I couldn't hear the difference so I got the Oppo
PS: this player the 'Primare BD32' is pretty much the same as the Oppo and the Cambridge but cost $5000 for a different audio stage, upgraded power supplies and a few user and input functions. Just get a good NAS, a nice DAC and be done.