The Dean of the Sydney Conservatorium of Music has been forced to resign after a Sydney University investigation uncovered concerns about the misuse of thousands of dollars on his corporate credit card.

Conservatorium Dean Professor Karl Kramer announced abruptly in April that he would not finish his five-year term at the elite Sydney institution, citing personal reasons. The Herald can reveal that Dr Kramer was asked to resign because of an ongoing investigation into his expense account.

The revelations again throw Australia's premier music institution into crisis, after a number of controversies dogged the woman that Professor Kramer replaced as Dean, Kim Walker.

The Herald understands up to $5000 in charges on Professor Kramer's card are under investigation, including a lavish dinner bill.

University administrators are believed to have begun querying Professor Kramer's personal expenditure a year ago.

Suspicions were heightened last year when conservatorium staff were listed as accompanying the Dean to a lavish dinner in a European restaurant with a bill that ran to nearly $1000.

"I wasn't even in the country," one staff member told administrators who rang to query the expense.

Professor Kramer declined to comment. He is understood to be contesting the validity of some of the expenditure.

The Herald understands Professor Kramer was told by university administrators  to offer his resignation or face immediate dismissal shortly before his shock April announcement.

"Concerns about the use of Professor Kramer's credit card were discovered through the regular oversight processes," a Sydney University spokesman said.

The University said it immediately withdrew Professor Kramer's access to his credit card and referred the matter to the Independent Commission Against Corruption. The ICAC is not believed to be taking further action.

A source at the university said vice-chancellor Michael Spence was outraged at the distraction the scandal had caused for bitterly disappointed conservatorium staff and students.

It is the second upheaval to rock the leadership of Australia's premier music academy.

Professor Kramer came to the helm in 2012 after fellow American Kim Walker's tenure expired in 2011 amid allegations of plagairsm and internal inquiries. She remained as a professor until leaving at the end of 2013.

The Pennsylvanian brass chamber specialist styled himself as the "therapist-in-chief" who had come to an institution "that needed to leave its baggage behind" after Professor Walker's tenure.

But emails from Professor Kramer soon emerged that suggested the tenor of management style was far from soothing.

Fairfax reported last year on emails he'd exchanged with an HR manager about language teacher Nicole Dorigo, who was made redundant.

"Duct tape can't fix stupid, but can muzzle it," one email from Professor Kramer read. "[W]ho died and left her queen?"

"Are we having fun yet?"

The dean referred to himself as "2K" in which the use of a "nuclear option" to terminate her employment was canvassed.

Professor Kramer emailed an apology to Ms Dorigo following Fairfax Media's inquiries.

Professor Kramer came to Sydney after a stint at the University of Illinois and after establishing himself through the Florida Philharmonic.

"I am leaving the faculty in excellent shape artistically, and the morale of the school has improved markedly since my arrival," he wrote to staff on the eve of the Conservatorium's centenary. "It is time for me to take a respite and consider my future plans",

The university praised his "significant contribution to the life of the Conservatorium".

Professor Kramer finishes at the Conservatorium on July 17.

Do you know more: jrobertson@smh.com.au