If you consider line out as bypassing analog volume control, every step of volume from this player is V-line out, as this player (as well as most other players) uses digital volume control.
Just consider this V-line out as a law avoiding trick. If you are using external amplifier, use fixed line out.
For sound stage you might take a try with lock range adjust changed to wide.
But to be fair, sound stage is never the strength of 300R.
Even with balanced output, 300R doesn't not match iBasso DX150, Sony's WM1A or even ZX300, in terms of the richness of the sound further away
300R provides fine details and tender sound, minimal noise on offline playback, etc