Phono Stage with balance control

In terms of stylus, I've noticed this phenomenon of a slightly off soundstage across several cartridges. The Benz I'm using at the moment has about 150 hours on it. I'm fastidious about set up: Mint Tractor and the HiFi News Test Record, and the arm on my Technics is adjustable in all planes.

In terms of recordings, I don't mean to construe balance as where an instrument is placed in the mix. To give you an example, I've got a NM 'Avalon' (UK 1982) and the 2017 half-speed remaster. Both, I assume, are mastered from the same mixdown, yet the 2017 noticeably shifts the centre of the soundstage to the right. I mention this as an example of ruling out set-up or hearing as the cause.

Aside from that, with headphones, even with digital sources ('Round About Midnight' in mono, for example), I'm at an age where I can detect a very slight loss of 'musical information' in my right ear. Not a gross hearing loss, not overall volume, but as though a bit is missing at certain frequencies. Never bothers me with speakers, but it can get distracting with headphones. Becomes really annoying if the source - like the 2017 'Avalon' - seems unduly tilted itself!

That's what led me to experiment with headphone amplifiers with balance control (Pathos Aurium, SPL Phonitor 2). In both cases - as you suggest - a noticeable degradation: transients go soft, the placement of individual mix elements lose definition.

This is what led me wonder about whether balance control is less destructive at different points in the amplification chain? Also, don't dual mono amps (Proprius) by their nature operate volume as balance control?

I also assume not all balance control circuits are made equally well? And if the circuit of the phono stage were dual mono, would this help the implementation of less destructive balance controls?

Maybe the Big Accession that's coming will answer some of these questions....?

thanks for the tips.

I suspect if it was azimuth/anti-skate then the soundstage would be off - in a consistent direction and extent - with every record I played.

On HiFi News Record I use the 300hz test tracks on Side B (tracks 1, 4, and 8) to get a ballpark anti-skate dialled in averaged across the side, then invariably dial it back by ear to account for less consistent modulation in the real world.