What do you mean by "Sound Quality"?

[Pim]

I voted for 'Objective: in the air, universal, repeatable' because if it's not repeatable it's probably in my head and not worth the trouble. Below is what I wrote on Stereonet Australia when the Curious USB Evolved was discussed and someone mentioned double blind test. I don't need a DBT to decide a piece of equipment is worth buying but what I describe below is certainly a test that says 'yes, there's an improvement and it's repeatable.


From Stereonet:

OK. This really sucks. I just wrote this really long story here, got a phone call in between, wrote some more and when I hit send it turned out I wasn't connected to the internet through my phone anymore. Lost the lot. So here's my second go...

I have a Devialet Original d' Atelier. It's a dual mono setup so it's got two USB inputs. Last week I took some time to make up a configuration with just the two USB inputs working. I named them the same in Roon. For those who don't know, the Devialet remote only has one button for source choice so you have to toggle through the available inputs. In this case just two times USB.

I played the same play list through both inputs and spent a bit in getting them to sync by pausing one of them a bit to let the other catch up. So then I could switch between inputs with no idea which was which. All I had to do is switch a bunch of times really fast to lose track of which input I was listening to. The only way to identify them was by looking at the screen on the amps but that requires getting up out of my chair and walking over to the amps (the screen sits on top)

I used an original Curious USB 0.8m long and an MIT SL Matrix 2.0m long for the test. The only other variable was the inputs and outputs to which I connected the cables. I did change them a few times too after the blind test. This I had to do sighted because there were two variables in place but it confirmed I wasn't hearing differences in inputs or outputs.

A bit about my ears.
My left ear has a drop around the 4kHz region and my right ear is fine. That means that when I listen to something bright, I get the perception of a balance to the right.

These are my findings.

There was what I thought was a perceived difference in volume between the two. I used a 1kHz test tone and my iPhone to confirm there was actually a volume difference of 3dB. So I adjusted the volume on the louder cable by 3dB in Roon and now I was comparing apples with apples. I just didn't know which apple was which yet.

Now I was listening at the same volume it was clear that one of the cables was just a bit less bright than the other. That meant to my ears that the balance on the brighter cables leaned somewhat to the right and through the other cable it was centred. A very easy thing to identify. Not once did I feel I had to guess.

I've always found that you hear deeper into the music when you get rid of a bit of glare/brightness so my preference was for the less bright cable. As it turns out the less bright cable was also the one with the drop in volume. It was the MIT SL Matrix.

I spoke with Geoff Blundell, importer of MIT and audio dealer in Tweed Heads about this drop in volume (Disclaimer. I do a bit of work once in a while for Geoff) There are boxes on either side of the cable which I thought were ferrite rings. But Geoff is not so sure. MIT are a bit hush hush about what's in their boxes so there could be a filter in there. That filter could get rid of the glare plus be responsible for the volume drop.

One thing is now clear to me. It's possible to make USB cables sound different. It might just be that it requires a filter but the difference is definitely there.

That finding sucks because now I'm going to spend more money again; I ordered an MIT cable in the length I need. And I don't even know how much it costs! Oops!