'04 2.7 tiptronic whining noise

[Coopstar]

Please help!
My wifes boxster has developed a noise recently, which is still intermittent but increasing in frequency, and the time the noise remains during driving.

The noise is coming from where I imagine the engine/transmission join, though it is hard to pinpoint as you will agree. The noise is a whining, which does not necessarily increase/reduce with engine speed, but remains wether gearbox in park, neutral or drive. The noise remains (or did this morning on a short drive), whilst car moving.

I have obviously ruled out driveshaft/bearing whine, as it is happening when stationary.
I am not very familiar with the mechanical/viscous connection between engine and gearbox in the auto style, so not sure what could be causing the noise. Suggestions in other vague forums include serpentine belt and tensioner.

It may be worth noting that last year we noticed the signs of a leaking RMS (couple of drops of oil on drive), but that seems to have stopped a couple of months ago. If the leak was more internal, what could this affect and could it be our problem?

Is there an ATF level I can check relatively simply?

Thanks for reading, any advice appreciated.

Regards,

Martin.