The pair pleaded guilty to manslaughter over the death of 32-year-old Mr Court who they set upon in a Mt Gambier street in 2017.

After inflicting the fatal blows, which included twice lifting the victim up and throwing him to the ground, they fled the scene, burning their clothes and hiding their car.

Sentencing the pair on Tuesday, District Court Judge Geraldine Davison said Mr Court had done nothing to provoke the assault.

"Your conduct was savage and the assault was brutal," Judge Davison told the brothers.

"It may have only taken 39 seconds, but that was all that was necessary to inflict the fatal blow or blows.

"The deceased was no threat to anyone, least of all you.

"This was a nasty, vicious and unprovoked attack by both of you in circumstances where there was no justification at all."

The court heard Mr Court did not fight back and was possibly unconscious when he was finally thrown to the ground.

He was left with severe head injuries and died after being flown to Adelaide for emergency treatment.

The attack had apparently been sparked by an earlier altercation between two groups, an incident the Von Stankes were not involved in but were told about in a phone call.

Outside the court, the dead man's sister, Sarah Danielson, said her brother did not deserve to die but felt the sentence imposed by the judge was better than the family had expected.

"Rex's life was taken too soon by two people who did not even know him," she said.

"We knew nothing could bring him back but hoped that the people who did this could at least be held accountable."

Judge Davison jailed Jordon Von Stanke, who was 23 at the time of the attack, for just over six years, with a non-parole period of four years and 10 months.

She jailed his brother Dominic, who was 19, for five years and four months with a non-parole period of four years and three months.

Australian Associated Press