I have recently upgraded my deaf HW7 receiver.

Started with the SA612, fed by the very stable , original HW7 vfo, feeding industry standard NE5532 audio chain . Performance was very good for its simplicity, but, the local station, totally blocked my receiver.

So, I opted for an AD831 , and found that judging from my ears, not much difference in noise and sensitivity, but, never experienced any blocking , at all, at any time. And, unlike the SA612, BCI , was absent, even with simple antenna input circuit.