Glad to hear you had an enjoyable DX session with the SR3. The Grundig AN200 loop is probably similar to my Radio Shack loop and my Select-A-Tenna, both of which add maybe 2 db to the loudness of the signals on my Superadios when DXing. You will probably find your Grundig loop useful.
Sometimes when using the loops with my Superadios, I don't have to move (re-angle) the radio at all, just more or reorient the loop.
Makes DXing a little bit easier. :-)
RE: the X-Band: Out here the X band is a toss up. 1700 usually has a mix of XEPE (near San Diego) and 2-3 eastern stations, including one in Iowa and two in Texas. 1690 is usually KFSG in California, sometimes with other stations behind (mainly the business station in Colorado). 1680 and 1620 have locals, so DXing is dicey at best, either the local has to have a computer glitch (silence), or a distant station has to be really strong in a tight null.
1640 has two regionals and a third that sometimes pops up. 1650 is a true DX channel, sometimes the Spanish Christian station in Denver predominates but you never know what you'll hear: El Paso, Arkansas, NOAA TIS's from the Oregon Coast, or mostly static. 1660 usually has two stations any given night, KBRE from California that plays rock, and a Spanish Christian station in the LA Inland Empire area.