Questions on utilizing optical and rca digital outputs

Also posted at digital section

I am running an Oppo BD 105 as a transport
unfortunately the Oppo only has optical and an rca coaxial digital out

the two dacs I would like to switch between

Audio Research Dac 3 - not as detailed but oh so musical

Conventional 75 ohm coax and  Toslink optical inputs

MHDT Orchid - very detailed and tonally accurate

“BURT”. Digital inouts.   -  75 ohm BNC, usb, rca and.  toslink optical

since the Oppo only outputs optical and an rca digital

would I just be better off swapping out
Digital optical cable between the

or is there an rca optical solution that handles the 75 ohm coaxial connection correctly?
any nice sounding bang for the buck rca  digital cables?

I'm not sure what you're asking but, first, there is no RCA optical output or cable that I'm aware of. Optical cables on today's devices have either a glass or plastic cable with a Toslink connector or mini-Toslink connector at each end. A digital cable with RCA connectors at each end has a copper wire conductor inside the cable. 
If what you're trying to do is connect the Oppo to both the Audio Research and MHDT DACs you could connect the Toslink output from the Oppo to one of the DACs and the RCA output from the Oppo to the other and on select which output is active from the Oppo.
Impedance (Ohms) doesn't matter in optical connections.  Impedance is for electrical signals, not light.

I do suggest you try a Wyred4Sound Remedy in between though, the ARC DACs really open up when fed a high frequency signal.


I agree with eric's recommendation of the W4S Remedy Reclocker. I have one between the optical output of an iMac and my Pro-Ject DAC and it makes a substantial difference.
I’d definitely use RCA and would highly recommend buying a 1m Apogee Wyde Eye digital cable from Amazon for 40 bucks and use that until you find something better. It flies under the radar because it comes from the pro audio world, which is why it’s so affordable, but it delivers. I much prefer it to my highly-regarded Stereovox (now Black Cat) XV2. Best of luck.
PS - I've found the Remedy provides a substantial improvement to pre-2010 DACs. 

After this point in time, more or less, the clocks in even inexpensive DAC's and digital filters, have gotten consistently better.  Perhaps because the clock's got cheaper.  I'm not sure, but the point is, after this a re-clocker is not really needed in good modern DAC's.