Okay guys, results are in.
First things first, I made a mistake with the length of the Nordost Blue Heaven. I checked my cables and they're actually 1.5m so that's the same length as the cheapo cable I'm testing against.
Before we go into the numbers, I need to say that this is as much as test of cables as a test of me actually noticing things. After about 1/3 of the way through the second session, there's just one thing I needed to look for and it was actually fairly straightforward. In the song Royals by Lorde, there's a sort of rhythmic sound that's like 3 snaps in succession. On the cheap cable, they're a little more lumped together so the sound more like one continuous sound. It takes some time to get it in my head, but I think as a result, the last 4 results of each sessions are all correct. Dunno, may be I'm imagining things again… if you put enough monkeys in front of enough type writers for an infinite length of time, the complete works of Shakespere is probably an inevitability.
Session 1: Y Y Y N N N Y N Y Y = 6/10
Session 2: N Y Y N Y N Y Y Y Y = 7/10
Session 3: N N Y Y N N Y Y Y Y = 6/10
Total = 19/30 = 63.33% => not statistically significant, as such it cannot be said that I can reliably tell the difference between the two pairs of cables.
That's not to say that there is no difference. To my ears there is. Apart from the above, the cello on All Through the Night (Yo-Yo Ma, Goat rodeo sessions) sounds a hair more natural and real on one of the two also. But it's a very small difference.
An important point I take from this is that while I'm happy with what the statistics say, having experienced the test first hand, I fear there's more to it than my simple setup can answer. You see, it's like if I show you two red tiles. The two are slightly different in that one is very slightly (but still visibly) darker than the other. Placed side by side, you'd clearly be able to tell. But if you're shown only one tile at a time and are asked to say whether it's the darker or the lighter, it wouldn't be so obvious. I feel it'd be better if I could compare what I hear currently against the same song played through either cable. Say if I could have three imaginary buttons, one to hear it played through the mystery cable, one for having it played through cable A and another through cable B and my job is to match what I'm listening to, to either A or B. May something similar exist with such facilities.
Now some might say that had I connected the cables directly, as opposed to through the SYS, it'd be more noticeable or whatever, but I'm wouldn't say that's likely. If we try this test on better gear, who knows. Had I tried it with an even more extravagant cable? I cannot say for certain but it is likely that the results would be similar. If anyone has these uber interconnects they're happy to part with I'd be happy to check for them.
Anyway, to conclude - there does not appear to be any difference that can be reliably identified (by me) between electrical analogue signals going through these two pairs of analogue interconnects between a DAC and a headphone amplifier.
Considering their price differences - roughly x50 - it appears to be one of the less effective ways to improve a hifi system. I have to stress, however, that I do not claim to be an expert with the best ears or possess a vast experience in high fidelity. These results are based on my gear and my ears. It may be different for others, I don't know.