What's wrong with them playing at the Festival Centre? It's a good venue.
Yes it's a good venue, but it's acoustics are terrible and dry for orchestral gigs. They actually installed a special amplification system to attempt to overcome this in the late 90s. It has the biggest stage in Australia (hence all that Wagner crap a whiles back) but is not really suitable for things outside of theatre/opera. The recent Mahler show could have been done there more successfully, but it was already occupied by another headline Festival act, and there's the rub. They could have done three performances with a concert hall in place and would have got full houses for each. Guaranteed.
My concern is the same as Paul Grabowsky's. The jewel in Adelaide's (and Australia's) cultural crown, the Festival, has become a slept-on laurel. Every Australian city has its festival now and Melbourne's is fast catching up as equally as good as Adelaide's, simply because it has more venues, all of them high quality. Adels needs a lot of investment in this area. The Art Gallery is struggling as you may recall from a recent outburst from its new director... fair enough. It is definitely one of the top three cities in the country as cultural hubs (with Sydney [by default] and Melbourne). But Melbourne isn't a "festival city" in the real sense. Adelaide remains the best in this respect, but must develop this from the 90s Barry Kosky vision it clings to. Things have changed.
Culture and the arts are one of Adelaide's great strengths. Never forget there are three recognised great arts festivals in the world: Edinburgh, Avignon and Adelaide. It won't stay like this forever without nurturing (which DOESN'T mean it should go annual) and to lose this would be for me (even from afar) the worst thing ever.