I've said this before and I'll say it again, there are headphones out there that can outperform the HD 540 in certain area's (and it's not a day and night difference), but you really will have to pay a premium for that sound that in some instances is only a 'sidegrade' as opposed to an upgrade.
And this is still my own experience too. I have been cleaning up a series of home theatre amps from Sony and Pioneer lately and the Ref1s always still sound organically and tunefully alive with all of them, even if not always the very best choice for a particularly amp. I kept the Pioneer VSX-D512, as it's a cracker of an amp with a really nice, clean and very tuneful DAC on board, with transparency
and depth perspective, for heaven's sake! It's just for my lounge system and has surprised me with it's lithe rhythmic abilities, especially with the already lovely little lithe and open Gale Mini Monitors MkII and a Jamo sub.
Good job that you have all those cans on hand to make the comparisons
It's still a genuine reference headphone for re-creating the life and humanity in music, instead of variances of electronic representations thereof and I'm fairly certain that it's the 600 ohm impedance that plays a large part in that, every other 300 ohm or lower Senn can I've heard doesn't seem to portray quite that sense of real Life to the same degree, regardless of age or youth, with a few exceptions from other brands ...... so I hear, since I don't own most of them. It could be just a rumour
The HD430s have a very similar communicative ability, though are certainly trickier to amp-up and lose out big time in bass depth and can overload easily with bass heavy tracks.
I will check out that cable though ....
I've been using the Ref1s with both the R2R-11 as a DAC running into a Magni 3 via the usual silver cables and with the Mimby/M3 combo and the Ref1s effortlessly and clearly show the differences between the systems, yet still sound fabulous with both. The R2R-11 DAC being warmer, denser, weightier/meatier, yet also darker and less transparent, though no less enjoyable for that. The Mimby/M3 noticeably more transparent, 3D and open. Both are so rhythmically adept and explore that same fantastic trait in the Ref1s. Brilliant.
Thanks for that update, Mr Git.