Why do digital cables sound different?

I've just read this thread with great interest.

I did some tests on my MBL transport and DAC (1621A/1611F) which I find interesting. It has multiple inputs and outputs, so I can run several cables in parallel and switch the input on the DAC via the remote, thereby making A/B very easy. It switches instantly too so there is no interruption to the music, making it even easier to detect any audible differences.

I ran a total of 4 cables in parallel, each on its own interface: 1 AES/EBU (either Synergistic Research Precision Reference (yeah, a regular XLR cable) or Audio Metallurgy GA-0 (a digital cable)), 1 RCA (I tried Gabriel Gold Revelation, Zu Varial, cheapo $1 plastic cable - all three regular ICs, and one digital $100 Monster cable), 1 Toslink (cheap Monster cable from the mid 90s) and 1 BNC (DIY copper, specced as a digital 75ohm cable).

Playing around with these in various configs and switching inputs back and forth (both blind and active, I used some fellow audiophile friends) - there is NO difference whatsoever between ANY of these cables.

I find this pretty mysterious to be honest. I've played with a lot of cables in the past and found many worthwhile improvements. But with this MBL duo, it's all the same.

Can someone perhaps shed some light on what is happening here? What have the Germans done inside the boxes to pull this off? I have no idea, and I'm not qualified to guess either - science isn't my forte. :)

Hi Osgorth.

German technicians are well-known perfectionists: ME-109 fighter plane, Panzer tanks, 88mm multi pupose canon,WW II standard 7.62 machine gun (which the US Army adopted as the MG60 in the late 50s and is still using 50 years later), the early Telefunken TVs and radio tuners, the VW bug, Porsche racing cars (especially, the 956 and the 962), anything optical, etc...

Perhaps MBL components are perfect and therefore not subject to improvement by cables.
Mike19

Did you test only by doing a rapid A/B between cables? In my experience, that methodology usually yields a "no difference" conclusion.

I love threads that last 7 years!

Osgorth, I think you've just done the test many here may have preferred you hadn't. Well done! From a technical point of view, there's no reason for digital cables to sound different provided they're made to a good basic standard, but there are plenty of audiophiles with bat ears who can 'hear' some amazing differences in various cables. I'm not surprized at your findings at all.

As for Drubin's comment about A/B comparisons; I've written in previous threads that this is the ONLY way to truly listen for discrete differences, as it allows the brain to do a true real-time comparison.

Long listening tests (where you listen for a longer period), then change cables and listen again requires you to compare the new sound to your memory of the first, which is less accurate IMHO. Not only are you relying on your memory of the sound, but you can introduce variations due to shut-down and restart of components, unlplugging and reconnecting cables and so on. Such comparisons work for hearing gross changes, but not the very small variations in digital cable sound.