The endless agonizing about oversampling digital interpolation filters and how they can badly affect the sound leaves one wondering if it is possible to create an ideal analog filter that would make a digital filter unnecessary. The common knowledge tells us that digital filters were introduced to simplify the design of the analog anti-imaging filters, i.e. reduce costs. What if one doesn't care about the cost? I'm pretty sure it is possible to create a heck of an analog filter for the amount of money some makers charge for their DACs, some of which, ironically, have no filters at all.