I just wanted to post some initial measurements and impressions here.
Keep in mind that the SR1a has an extremely unique fit to it that makes the tonality change depending both on the angle of the flaps and the forward/backward positioning. With that said, I took all of these measurements with it at the optimal position for how I wear it (what sounds best to me).
Apart from the bass roll-off, I think this measures (and sounds) really quite good. The upper midrange and treble balance in particular is really nice. With the bass, when you move the flaps inward, it is possible to get a bit more energy in the mid and upper bass, but at the same time it also loses a bit of treble presence, which wasn’t to my taste. The midrange forwardness seems to be there on every measurement I take where it’s at an optimal position for the rest of the FR, but I don’t mind that at all. When you adjust them forward/backwards this does change a bit as well.
Okay now onto a few other things. For the most part, I find the detail retrieval and image clarity to be excellent. Treble and upper midrange detail is really quite good. For mids and bass, I feel like that’s the SR1a’s weakest point. For other technicalities, I find it’s not a particularly punchy sounding headphone, so not the greatest for dynamics. And I don’t think this is just due to the bass roll off, because even when adding a low shelf by a few dB it still doesn’t give me much punch. I think that’s okay though because it does sound sufficiently lively throughout the rest of the FR - not unlike the HEDDphone, although I’ll have to spend more time going back and forth to get a proper sense of that.
Soundstage is one of the more strange aspects of the SR1a to my ear, and in a way kind of disappointing. I don’t find it as spacious as I thought it might be. I think this is because when I position it in such a way that’s optimal for tonal balance to my ear (what I like, and as close as possible to what the measurement shows), it loses quite a bit of the space and stage characteristics. So I suppose it’s not to say that it doesn’t have them, like when I move it forward on my head I get the increased sense of space one might expect. And when I open the wings up wide, it does sound more spacious and open, but this also has an impact on the FR that I’m not a huge fan of. So I think if you want the space and stage, it’s there with the SR1a, but that may also be at the cost of a bit of tonal balance.