Bass nerd (like most of us) here. I knew from experience that not having a strap pin up on the horn above the 12th fret could cause bass to lean forward while playing (as well as balance issues). Still went ahead and bought lifetime bass, Alembic Stanley Clarke. Bass balances extremely well on strap (pleasantly surprised given body shape and strap pin location). However, it does tilt slightly forward (away from my body) -- which was causing me physical discomfort (aches in my back muscles from likely compensating and unconsciously going with the forward lean). Major (understatement) source of "OMG, what did I do?!" Price tag on that thing is um...hefty. Majorly concerned/bummed out, until...
Long story short:

Long story short:
- Switched my normal inclination as a righty to play with both feet parallel, or left foot in front and sitting back on right foot. Now doing exact opposite.
- Bought the hard rubber wedges shown (meant for squatting while weight lifting)
- Now, play with my right foot forward (either fully on top of the wedge itself, or even just putting my toes on the wedge with heel still on floor is enough to tilt bass back into perfect position). My slightly raised knee is 'automatically' tilting bass back.
- The rubber wedge is actually ergonomically comfortable to stand on, and looks like a volume pedal...
- Just played a two-hour jazz gig with zero pain/back discomfort. Once or twice, was aware of left back foot feeling a little tired/"asleep" -- just had to shift around a little to reset. I'll take that over aching back muscles and pain any day.
- And yes, the bass is awesome; love it.
