That hiss you hear is the noise floor of the BeachTek. It sounds like you may have the gain stage of the BeachTek too low, so when you raise the levels with the camera, you raise all the noise up with it. To get a good level with the BeachTeks (and assuming you don’t have a mixer with reference tone) I would do this: plug your mic into Ch. 1 of the DXA8. Turn on phantom power (if needed) after you’ve plugged in the mic. Next, engage the limiter on that input. Now do a mic check (approximating your actual levels) and turn up the gain until the limiter just begins working on the loudest signals. Once you’ve found that level, back off the gain maybe a half step (not much, but a little). I would be inclined with that setup to go ahead and leave the limiter engaged. Now you have good gain staging for that input. Repeat for mic input 2 of the BeachTek (if you’re using it). Now you can safely set levels on the FX1. I would set the levels so that the non-limited peaks of your audio peaks at around -10 on the camera (assuming it is a digital camera). This gives you 10dB of headroom left at the camera but the limiter of the Beachtek should keep you from going over absolute 0.