• Registered: 2023-12-10
  • Posts: 18

Topic: ADI-2 Pro FS R: second separate spdif coax source input via AES ?

Sorry, this must have been asked before;
Is it possible have a second separate & simultaneously SPDIF coax input signal via a SPDIF to AES adapter connected to the breakout cable ?

If so, the two independent SPDIF coax sources are 0.5 Vp-p (75 Ω), does anybody know if I can use a 110 Ohm cable to connect those to the AES input of the ADI-2, to use a 110 Ohm RCA to AES cable, something like this ?;
https://www.thomann.de/nl/pro_snake_aes … YwQAvD_BwE

Or do I need an 75 > 110 Ohm adapter, something like this ?;
https://www.thomann.de/nl/neutrik_naditbncm.htm

Am I correct, once the SPDIF coax sources are connected, I can route them separately / independently in Logic to XLR out en Phones 3/4 ?
Will this also work in standalone mode ?

A lot of questions, thnx in advance, happy hollidays !

2 Reply by KaiS (edited by KaiS 2023-12-24 14:08:30)

  • KaiS
  • DAW Mastermind
  • Offline
  • From: Germany
  • Registered: 2020-02-05
  • Posts: 3,525

Re: ADI-2 Pro FS R: second separate spdif coax source input via AES ?

1. ADI-2 Pro‘s AES input in principle accepts SPDIF Coax signals.
According to my experience it might or might not work with a simple cable adapter, SPDIF signal level is at the lower edge of what’s needed.

With an 75 Ohm to 110 Ohm converter it should work in all cases.

For short distances < 3 m the cable type doesn’t matter at all.


2. Manual page 38 shows, e.g. in AD-DA mode SPDIF and AES can be routed to 1/2 or 3/4 independently.
E.g. AES to 1/2 and SPDIF to PH 3/4, or vice versa.

KaiS's Website

  • Registered: 2023-12-10
  • Posts: 18

Re: ADI-2 Pro FS R: second separate spdif coax source input via AES ?

Thnx !

4 Reply by rcstevensonaz (edited by rcstevensonaz 2024-06-02 21:42:18)

  • Registered: 2020-12-24
  • Posts: 24

Re: ADI-2 Pro FS R: second separate spdif coax source input via AES ?

A few additional questions related to this thread...

1) @MichielDeBink (or anyone else), were you able to successfully connect a RCA S/PDIF output to the AES XLR input? If so, how well did it work and were there any issues?

2) Can the RME ADI-2 Pro FS R apply sample rate conversion (SRC) on both digital inputs (AES, S/PDIF) at the same time while still using RME's high quality internal clock? For example, when using USB Multi-Channel mode to route both digital inputs (e.g., network streamer, CD/DVD) up-sampled at 96K to a PC for mixing and EQ.

3) Even through the cable doesn't matter if < 3m, would it be slightly better to use a 75 ohm cable (to match the consumer S/PDIF device) or a 110 ohm cable (to match the AES port on the RME); or is it completely irrelevant at that length? That is, for a situation where you already have both 75 and 110 ohm cable to use.

5 Reply by KaiS (edited by KaiS 2024-06-03 06:21:38)

  • KaiS
  • DAW Mastermind
  • Offline
  • From: Germany
  • Registered: 2020-02-05
  • Posts: 3,525

Re: ADI-2 Pro FS R: second separate spdif coax source input via AES ?

2) There‘s one SRC / Sample Rate Converter inside ADI-2 Pro / ADI-2/4 Pro SE.
It can be assigned to AES or SPDIF, not both.

Steady Clock FS is always active for lowest jitter.


3) In digital interconnections there‘s not really a “slightly better”.
If does work - or doesn’t.

ADI-2’s Steady Clock FS cares for optimum clock recovery in all cases.


There might be a situation where the digital interface’s signal levels are just at the edge of working or not working (weak SPDIF connected to not-so-sensitivity AES).
Even then, for short cable length (< 3m) the cable type or impedance doesn’t make a difference.

For long distances impedance matching is mandatory anyway, as reflections at the cable ends can render the signal unreadable.
For short distances reflections are in sync with the signal and stay unvisibe.

Sample rate is a factor too:
Higher sample rate -> shorter cable (in case of impedance mismatch).

This is related to speed of light and digital signal’s frequency.

KaiS's Website