Sitting Position for Double Bass
Sitting position should be approached from a standing posture. After the student has learned where the bass balances with their body while standing, they can sit down on a stool and balance the instrument in the same way. The student should not slump over the instrument in sitting position. Depending on the height of the stool, the endpin may need to be adjusted when going from standing to sitting.
The advantages of sitting:
1) Extra leverage gained from your arm weight, because of the increased angle of the instrument. This is particularly beneficial for French Bow players.
2) More comfortable for long rehearsals.
Advantages of standing:
1) Extra leverage can be gained from weight of the instrument, by leaning the instrument slightly forward into the bow. This can be especially beneficial for German Bow players.
2) Freedom for body movement.
Many bassists I know sit in orchestra rehearsals but stand in solo recitals.