A man accused of stabbing his wife 30 times at their southern Sydney home was affected by depression at the time of the fatal attack, two psychiatrists have told a court.

Haydar Haydar allegedly suspected his wife Salwa Haydar of having an affair when he stabbed her to death following an argument in Bexley in early 2015.

The 60-year-old is also accused of injuring his then 18-year-old daughter, Ola Haydar, as she tried to intervene.

Haydar has pleaded not guilty to murder, wounding with intent to cause grievous bodily harm and reckless wounding, but has pleaded guilty to manslaughter.

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His lawyer is arguing he was affected by an abnormality of the mind, and two psychiatrists told the Supreme Court on Monday they believed he was suffering from depression at the time of the alleged murder.

Dr Stephen Allnutt said he found Haydar had a mild to moderate depressive disorder, while Dr Bruce Westmore rated the accused's condition as moderate to severe.

"The provocations from the wife were very minor," Dr Westmore said.

"But he has had this extraordinary reaction to it, which I suspect had he not been depressed would not have occurred."

Dr Allnutt said the issue for him was whether the alleged murder was impulsive and unplanned, suggesting a loss of control, or if it was premeditated.

"In the absence of loss of control he does not have the defence of substantial impairment," Dr Allnutt said.

Both psychiatrists said they considered a constellation of symptoms in making their findings, including Haydar's recollections of appetite and weight loss before the killing, but his daughter Nour told the court she didn't notice any weight loss.

"He looked the same to me when I saw him, I didn't notice any physical differences," she said.

The trial continues before Justice Peter Garling alone.