When the Reds did get their hands on the ball, they displayed impatience and poor structure.
Hunt often found himself short of front-foot runners due to the Brumbies' blitz defence.
It took the Brumbies just five minutes to get on the board.
A strong run by prop Scott Sio sucked in several midfield Reds defenders, with fullback Robbie Coleman then finding space out wide.
Christian Lealiifano showed no early signs of his 2014 kicking woes, knocking over the conversion and then three penalties to put the Brumbies up 16-0 after 28 minutes.
Hunt was harshly penalised for not using his arms in a tackle in the 19th minute, and the resulting lineout looked destined for a try until David Pocock dropped the ball over the line from the back of another rolling maul.
Hunt finally put the Reds on the board with a 40m penalty goal in the 34th minute, their lack of chances partly due to their sloppiness at the breakdown.
Man-of-the-match Pocock was otherwise solid in his comeback game from his second knee reconstruction, likewise Stephen Moore, who came on in the 50th minute.
The Reds gave away their 14th penalty in the shadows of halftime, compared to the Brumbies' four, and it cost them dearly.
Joe Tomane scored in the corner after a well-executed rolling maul for a 21-3 lead.
Referee Angus Gardner finally gave Horwill his first yellow following numerous warnings after halftime, with Toomua rolling over Hunt two minutes later to extend the lead to 28-3.
Halfback White then grubbered the ball through Will Genia's legs and outraced Hunt to the ball to bring up the Brumbies' bonus try.
Toomua put over Tevita Kuridrani for the fifth try, before reserve back James Dargaville crossed over on debut.
Brumbies coach and World Cup-winning five-eighth Stephen Larkham said it was difficult to give Hunt's debut a rating due to the dominance of his forwards.
"He didn't feature too much," Larkham said.
"He wasn't really a threat in attack, because our defence was so good in that area.
"Defensively, he was very solid. He put some big shots on, but it's very difficult when the weight of possession is against you."
After almost two full seasons on the sidelines with consecutive knee injuries, Pocock said it was good to get a full match under his belt.
"I'm feeling good. I'm looking forward to the day that people don't ask about (my knee)," he said.
Reds coach Richard Graham admitted he was surprised by his side's poor discipline.
"When you're constantly getting marched down the field, it's hard to get into the game," he said.
"White is probably the most accurate length kicker. We were always under pressure."
