I'm currently upgrading a sonar project, where the receive signal would be amplified by the AD8331 followed by the AD605 (we were using an on chip A/D so lost sacrificed a lot of signal information). We're now upgrading and moving towards using an external differential A/D. The AD8331 op amp datasheet discusses it's application in ultrasound systems and ideal ADCs. My application is for sonar and therefore operating at a much lower frequency ~250kHz (rather than MHz). I'm trying to select an ideal A/D. Is there any reason why a system optimized for higher frequencies would not perform as well at lower frequencies? Or can I just follow the guidelines described for ultrasound applications?