Help Stepper Motor GRBL T6560

I sat down today to try and GRBL configured properly for my drivers and motors. I think I made some progress on the settings, but I feel like it should be smoother and have less vibration than it does.

Here are the components I am working with:
200 steps/rev 2A

Driver board:
SainSmart CNC Router Single 1 Axis 3.5A TB6560 Stepper Stepping Motor Driver Board

Everything Else
Arduino UNO+GRBL 0.8c

Here are the settings I began with, followed by my actions and notes:
Driver Board-
Current max = 2A
Stop Current = 50%
Microstepping = 1x
Current Decay = 0

NOTES=Lots of vibration, very loud, sounds like stronger and lower pitch version of “Wheel of Fortune Wheel”

$6=0.1 ->no change, changed back to 0
driver board current ->change to 1.6A, no change, changed back
change to half coil wiring on motor->no change, changed back to full coil
$1=6.562->faster, but still vibration
$1=13.124->more of a “whining” at high speed, still vibrates lots
$3=3->no change, changed back
driver board current to 1A->little quieter
driver board current to 0.5A->quieter
microstepping->2x, much quieter
$1=26.248->seems better, still has some vibration
driver board current to 1A->vibrates when accelerating (at start and end of moves)

Here is the video link, Sorry the sound is very low:

Any thoughts on how I can make it smoother/quieter?

Use microstepping.

I am running it at 2x...

I am curious how amp rating works with a 4-phase, unipolar stepper with 2A/phase. Clearly not all 4 phases are activated at once, but is there residual draw from the previous phase or is it fully off when the next phase is activated.

Your driver has these stats:

Rated voltage: DC 12V-24V
Maximum current: 3.5A

What would start up amp draw be for a 2A / phase motor? And with rated Vmin of 12V, how does that impact your stepper with a rated voltage of 3V?

I am about to embark on a similar journey with weaker unipolar steppers, so am very curious if someone can fill in the blanks.

As I understand things, the voltage, current and resistance in the specifications show what current the coils can take and the voltage that supplies that current, bearing in mind the resistance of the coil.

Because coils are inductors it takes some time for the current to rise after the voltage is applied and this time may be too long if you want the motor to turn quickly against a load. A common way of getting over this limitation is to drive the motor at a much higher voltage so that the maximum current is reached in a shorter time. However then it becomes necessary to limit the power to prevent the current increasing beyond the allowed maximum. Some of the stepper motor driver boards look after the current limiting function - for example Pololu - A4988 Stepper Motor Driver Carrier which has a small potentiometer that is used to set the upper limit for current.

If any of this is wrong it would be very helpful to me if someone would correct me.