Many people here asked how to check the Si570 working without test equipment and/or antenna. Finally, I tried to do this with an FM receiver and the test works just fine.
I assume that you are at the stage when the USB device is recognized and you can run CFGSR. Run it and tune to 8.25MHz (33.0 at the Si570 output). The third harmonic of 33.0 should be clearly heard (as silence) on a nearby FM receiver tuned to 99.0MHz. As you tune Softrock up and down, the signal should disappear. In case you have a station on 99.0, other frequencies should work just as well. I didn't attach an antenna to my Ensemble RX II, and it is in a KM5H enclosure.
I've also tried the second harmonic of 52MHz (13MHz tune frequency), and it is just a little bit weaker. I had to place my Kaito 1102 right next to the SR.
Hope this helps somebody,