Pryso,
You have to be in the sweet spot to fine tune azimuth by ear. That's the only place you can hear your sytem's L/R imaging at its best.
Don't use test tones to set azimuth by ear. They wouldn't help. Use music, preferably higher pitched instruments and/or vocals. Our ears are more sensitive to directional cues at high frequencies.
Don't use rock, use well recorded acoustic jazz or classical. (Who cares about azimuth for rock anyway? Oops! There I go!!)
It's best to rough azimuth in by eye first by making your stylus as close to vertical as possible. No matter what your meter or ears tell you, you don't want your stylus significantly off vertical - for the sake of your records and your stylus. If you have to angle it more than 1-2 degrees something's wrong (probably with the cartridge, few are perfect).
Before attempting to fine tune azimuth any more closely, make sure all of the following have been done:
1. your cartridge is well broken in
2. VTF is optimal (set by ear, not just by what some scale reads; if you can't set VTF by ear you certainly won't be able to do so with azimuth)
3. Antiskating is optimal (set by ear, not by what some dial reads; ditto for needing to be able to do this by ear before attempting azimuth)
4. the system and cartridge are warmed up, play 2-3 sides before you begin.
I can't describe what to listen for any better than Jtimothya did:
Listen to a female vocalist who sings center stage. Adjust azimuth to get her mouth/voice as small/narrow as you can. Incorrect azimuth tends to splay sounds horizontally, making instruments and voices larger (spread wider) than they will be when azimuth is correct.
When you think about what crosstalk does to a stereo image, you realize that's a perfect description.
