The SR1a and Fine Tuning Channel Balance; something to consider:
Imaging or a 3 dimensional sound stage/field in front of you? With speakers (or live) you have L-R and R-L information going to each ear in addition to the L and R information. Without that, sound stage and imaging will be affected. While the SR1a’s open wing design allows for a minimal amount of information to cross over it’s just not enough as occurs live and with speakers so the sound field in front of your eyes will still be different or possibly mostly inside the head. Angling the wings out more may help.
If you were to draw a straight line through your head from center of chin to top of skull the two halves would not be equal in appearance, shape or dimensions. In particular the eyes and ears would be at slightly different heights and distance from the center line of the nose. Ears are generally not the same size in the vertical and horizontal and in height of the ear canals which could be at slightly different positions on each side of the skull. Additionally the shape of the ear canals and how they run in may not be identical. And to make things worse it’s unlikely both ears will respond identically to a frequency test by an audiologist.
With a dynamic driver or planar magnetic (or Electrostat) I position the cups so my ears feel equally installed inside each cup with the ear pad around the perimeter of the ear. These drivers generate sound over the size of the driver / diaphragm and fill that ear cup.
Now take the SR1a, you don’t have that much physical feedback as the points of contact are the 2 narrow vertical pads on either side of your head roughly in the upper jaw area and the ribbon is a narrow vertical line source.
Place the phones on in the normal positions you use that feels right. Play, say, a 1KHZ test tone, white or pink noise that’s in phase and recorded equally loud in both channels. (A centered vocal soloist would work as well, provided he was recorded on center - that’s why I like some pink or white noise). Hold the right wing in place and move the left wing in very slow steps fore and aft. Do you find a spot where it really locks that test tone in the center of your head which differs from your usual placement. Now repeat the same test holding the left wing firm and moving the right wing. This is the ultimate balance control. The splay of one’s ears and degree of open or closed wings could have an effect as well. If each wing is parallel to each ear that should work well enough.
That’s been my experience with channel balance and the SR1a. My dynamic and planar magnetic drivers don’t really have enough “comfortable” space inside the ear cup to make a lot of placement changes with my ears but because they do seal around the ears the way they do the chances are I’m less likely to run into a channel balance / imaging issue that is the fault of the HP provided one of the drivers isn’t damaged or cable connections are loose or intermittent.
Once I lock that center position for say a test tone or solo singer, the sound stage really improves and imaging as well. It only takes a few seconds for me to hit that spot on the fly now because of familiarity and knowing what I’m trying to do with placement, and what I know I can and can’t achieve with an earphone.
Just some random musings on the SR1a and how I fine tuning channel balance. Something worth trying and there’s no cost involved!