I'm sorry that I cannot answer the technical question, but to
give some related comment, I've got an S350 DL and found
it to be one of the best-performing MW radios for actual
long-term listening to stations which are too weak to enjoyably
listen to using other radios. The digital readout makes me
pick it up to use instead of one of my GE SuperRadios.

I am speaking of daytime listening to a weak station located
in Illinois which is set up to service that region as opposed
to the Missouri side of the river here in St. Louis, where I am
located. There's a new station on 1510 kHz, WXOZ, that has
been playing 50s/60s oldies just about all the time, though
it announces that it will change over to talk radio on weekdays,
with this music being mainly on a Sunday-afternoon show.
Anyway, most regular radios get it very weakly with a lot of noise
but the S350 DL, using the "Wide" bandwidth setting, gets it nice
and clear. Aside from the GE SuperRadios, it takes a
more-expensive digital radio, like a DX-398/Sangean 909, to get
such a listenable signal. A Kaito/Degen 1103 will pick it up, too,
but the sound is much better on the S350.

I don't really MW DX, though, so I haven't spent much time on
night-time weak-signal testing using the narrow bandwidth.

73, Will