CD vs SACD in STEREO

I think Richard Brand covered the specifics of your equipment.  I would go with whatever DAC offers you the native DSD conversion .  You can research that OP on your own.  The Oppo 103 probably does but I don’t know about the rest of your gear.  
 

I have had very bad luck with Marantz products and their missing in action customer support.  While concerns about Bose ownership of McIntosh are valid, I have heard the DACs in Mac Processors and they are quite good.  They really shine when connected to a Mac SACD player through the proprietary link but are also great via HDMI from an Oppo outputting DSD.

@richardbrand "I think Richard Brand covered the specifics of your equipment.  I would go with whatever DAC offers you the native DSD conversion .  You can research that OP on your own.  The Oppo 103 probably does but I don’t know about the rest of your gear. " Richard, what is your comment on my hardware with respect to DAC for both systems? Use built in Oppo/Sony player DAC or receiver (Onkyo/Denon) for 2 and 5.1 channel (system 1 and system 2)? 

Update: Just found your earlier reply Richard, thank you. Never noticed the missing analog output on the Sony x700. But quite surprisingly, the Oppo not doing ATMOS. Does that also mean no DSD? May have to swap Oppo on Denon to become 2nd system, and cheapo Sony X700 on Onkyo for 'main system 1' duty. An Then listen to my new verson of DSOTM!

I'm sorry if this is a little off topic. But as regards Dire Strait's Brothers in Arms. First off, I am a huge fan of both Dire Straits and Mark Knopfler. Despite that, I have to say that Brother's in Arms is a dreadful* sounding album. It was recorded on a Sony PCM 3324 DASH (Digital Audio Stationary Head) tape multitrack which had a maximum resolution of 48/16. Any higher resolution version of the recording is still limited by on the sample rate/wordlength of the original tracks on the multitrack. If the SACD sounds better than the original CD - which I think it does - its most likely because (a) it's been remastered the original 48K sample rate, rather than the CD which would have been downsampled to 44.1.

*Thin and sterile - it, The Nightfly and Bop Till You Drop all have a similar character. Brother's in Arms is made worse by a horrible 80's drum sound.

@kraftwerkturbo 

But quite surprisingly, the Oppo not doing ATMOS. Does that also mean no DSD? 

Not at all.  Dolby Atmos and DSD are completely different animals!  DSD is mandated on the SACD layer of SACDs, whereas Dolby Atmos is essentially high-resolution PCM probably delivered on Blu-ray disks.

Blu-Ray and SACD media are both high capacity, and they may share the same short-wavelength lasers in a universal player / transport.

A couple of oddities!  You can always exactly convert DSD to CD-quality PCM, but it does not exactly work the other way round.  This is because DSD samples at about 2.8-MHz and higher multiples thereof, whereas CDs samples at roughly 44-kHz.

Dacs that use sigma-delta technology are far more likely to natively process DSD than ladder-type dacs like R2R which are designed to mitigate PCM;s monotonicity problem.

To find out how your dacs work, you need to discover who makes them, and their exact model number.  Possibly from the user manual.  Then you can find their spec sheets, and start reading between the lines for what is missing.

According to ChatGPT your Onkyo uses AK4458 384 kHz/32-bit DAC (Digital-to-Analog Converter).  

These converters are made by AKM and the datasheet says they max out at 768kHz PCM and 11.2MHz DSD.  They are 8-channel dacs as well.  Quite superb, in my opinion.

I look forward to hearing how the little Sony compares to the Oppo.  My prediction - no audible difference.

@yoyoyaya 

There have been at least 3 re-masterings of Brothers in Arms for SACD.  I only know the 20th Anniversary one and the original CD, which of course was so popular it really established CDs in the market.  I still have Philips’ CD sampler which also features Dires Straits Once upon a Time in the West from memory.

Recorded on a 24-track Sony 16-bit machine, possibly at 48-kHz sample rate, mixing was done digitally.  The resultant acoustic is far from natural, to say the least, with pin-point percussion effects.

Digital mixing is problematic, especially if only whole numbers are allowed.  You have to multiply by fractions (really, divide by a whole number), and add the results together.  Very quickly the least significant bits become totally screwed up because of multiple rounding errors.  The more original tracks you start with, the smaller the starting numbers will be on average.  I believe this is why classical recordings made in a natural acoustic have been excellent on CD from the get-go, whereas pop/rock is the opposite.

There’s almost no technical information on mastering for the anniversary SACD.  But the results are clearly better than the CD

Only very recently has it become feasible to use floating-point numbers for mixing.