I have read many times of the visual difference that a larger sensor returns when compared to a smaller sensor. Many photographers attribute "the Medium Format look" at least in part to the physical size of the sensor, be it film or digital.
All else being equal, I do not understand why the physical size of a sensor should make the slightest bit of difference to what is recorded. As far as I am aware a sensor crops from the image circle of the lens mounted in front of it. No more, no less.
In order for a comparison between sensors of different physical size to be made on a like for like basis, depth of field would require to be matched. In addition, the same lens should be used. It is probably not possible to normalise the difference in colour from a range of sensors, though I dare say that comparing cameras from the same manufacturer would help to minimise any difference that existed. However, as far as I am aware "the Medium Format look" has never been claimed to relate to colour - velvia on a Small Format camera returns the same colour characteristics as it does on a Medium Format camera, does it not?
The thought occurred to me that it should be relatively simple to test for the difference in look, if any, insofar as it relates to sensor physical size for a range of formats. Has anyone ever carried out such a comparison? Is there any reason that such a comparison would not be valid?