See https://forum.rme-audio.de/viewto … 23#p219923

1. The same ground, pin 1 of the D-sub, is connected to AES in and out.
This is even linked to ADI-2 chassis ground internally.

The XLR plugs‘ casings should be connected to ground either, for blocking HF.

2. On short interconnections, less than a few meters, the impedance matching isn‘t critical.
Typical microphone cable is close to 110 Ohm and can be used for AES.
Video cable had 75 Ohm and fits to Coax digital anyway.

WC isn‘t present on the 9-pin D-sub.
ADI-2 FS-clock perfectly recovers WC out of the selected source.

75 Ohm cable is video standard.

You find those cables everywhere: coax antenna and satellite cables for FM radio and tv sets, inside Scart cables, domestic video cables with (typically yellow colored) RCA plugs etc.

As mentioned, for short interlinks it’s not mission critical at all, bare wires would do (not that I recommend this).
But typical cheap accessory RCA cables for audio do fit too.
The plugs in between don’t represent a problem either.

The mentioned WC cabling is another story, it is about end-termination, which indeed is very important to avoid reflections AND reach the correct electrical signal level.
But, in your case end-termination is already built into each device, you don’t need and by no means should care about it.

So don’t worry too much, use what you have or find, it will do.

Final tip:
SPDIF digital Coax for distances beyond specs can be achieved with cables for digital satellite dish connection, I’ve done 25 m with no problems.
These 75 Ohm cables have ultra-low loss, as the are made for 2 GHz, almost 100 times more than the ca. 25 MHz you find in SPDIF Coax.
These cables are readily available in tv stores and very cheap.

Ive been building a parts list for an ideal transmission, mostly for personal education, as these components are expensive. Im gonna go for your @KaiS advice to use what I have. with some minor upgrades.

Is short what Ive come up with: DB-9 contact with 5-pin and two 75ohm coax inserts (*4 for ADIpro and UCXII). Special solder for thick gold plating. Micro coax cable. Just for coax inserts its €40, so this is just a rabbit hole of expenses. Like I said this box wont see more than a few meter spdif anyway. It would be to maintain impedance, but the most benefit would be a professional look.

Good idea though. I can test the system with cheap TV 75ohm cabling. I think I have some(alot) stashed. Just to run bittests and get some idea of the quality.

Most intelligent solution, I think would be to drive a whole length of cable from ADI2pro DB9 to output and use a rubber gasket and stoppers through BO-chassi, At least this does not subtract from original BO-968 solution. Then again I have the standard db-9 contacts and kinda looked forward to solder and build that stuff.

-A lot of overkill in your list

You think so? These contacts are for labs and hospitals. Overkill is kind of the intention, but its also functional even too much.

-Coax inserts??

These are something like usual DB contacts, and there is a whole range of them. They have some big through holes plus pins. These holes can be use to transmit high power, coax and even pneumatics. Its just standard parts. I found the perfect parts for my use; a DB9 sized 2 holes and 5 pins. Which eqals 2 coax + AES I/O in one contact, with 75ohm impedance all the way.

Naturally these cost more than standard DB, maybe €30+/contact, this is for asembled contact, esp coax is expensive with 2/3 of that. The coax look good quality with solder pot and crimp.

About solder I read a some papers about soldering gold plate, the problem arises with tin mix solders and gold layer above 1.5 micron. Search for "gold scavenging" + "solder". The contacts have au layer right at threshold. This doesnt worry me so much as I could use indium and led pellets for a lots of cool stuff, not that expensive either. You can solder glass to metal with Indium, and it even sticks in cryogenic temp.
Thought was to make InPb 50/50 and use that. This is some milspec stuff and certainely because of mechanical properties of the joint. As gold - tin intermetallics can progressively degrade the joint, above 1.5 micron.

The cable is recomended for the coax contacts and typically come in 100m rolls at €3000. Its about size of jacket and insulation not magic. If I could just find a few meters.

-Digital bits either come through or not, there are no “better sounding bits”, whatever you can read in some esoteric audiophile forums.
Imagine, the bits are not even transferred in the order they are converted to analog, but have to be “sorted” in the converter when received, and internally in the converters there are a number of digital processing intersteps!-

I know that drill! Totally agree. I dont expect any special or magic sound or recovered bits. No rabbits from the hat