We use a pair of cs5381 ADC's in a high precision signal analyzer, and have noted some pretty bad performance on about 75% of the chips that we have been getting in lately. This all started with date code 1644(yy.week). We have attempted to contact Cirrus to see what may have happened, but aren't getting much response. The noise floor performance on some individual channels is actually considerably worse that the "budget" 5361 chip. Has anyone else notice increases in idle tone amplitude, intermodulation noise at high frequencies, or just overall high noise floor in general?