High current outlets do nothing when the circuit itself is being pushed to its maximum, though. If enough amplifiers are on that circuit, the voltage drop will be significant, so a second circuit should be run, both on the same phase. Also, some power supplies aren't as well-regulated as others. A tube amp designed for 120VAC that ends up on a circuit that is only delivering 110VAC may see a 30V drop on the power transformer secondary and it could lose more on the B+. That will affect the bias as well as the plate voltages. Not much of a problem unless the amp is designed for 110VAC and it ends up on a 120+VAC circuit- the power supply caps may not be able to handle the >500VDC B+ when the caps are rated for that, or less. This would only apply to old equipment but it can still be a problem.
I would rather run a new circuit than try to share one with a large group of equipment, lamps, etc.
Also, for those who aren't familiar with "star grounding", it isn't a physical thing, it's purely electrical. It means that the ground reference for all pieces in the system are equipotential. Potential refers to Voltage, since voltage is 'potential energy' and equipotential means there's no voltage difference between the pieces. This shows up as zero measurable Volts between the chassis of each piece and any other.