Untested patch:

Index: D:/eclipse/SN/lib/SDI/SqueezeNetwork/Controller/API/Shoutcast/V1/OPML.pm
===================================================================
--- D:/eclipse/SN/lib/SDI/SqueezeNetwork/Controller/API/Shoutcast/V1/OPML.pm	(revision 5047)
+++ D:/eclipse/SN/lib/SDI/SqueezeNetwork/Controller/API/Shoutcast/V1/OPML.pm	(working copy)
@@ -184,6 +184,10 @@
 	my $bitrate_limit = $c->stash->{prefs}->{plugin_shoutcast_bitrate_limit} || 999;
 	my $sort_by       = $c->stash->{prefs}->{plugin_shoutcast_sort} || 'lc';
 	
+	if ( $query =~ /Top500/ ) {
+		$sort_by  = 'lc';
+	}
+	
 	my $items = [];
 	
 	my $tunein_base = $c->stash->{sc}->base . $stations->{tunein}->{base};


Additionally the cache should be invalidated if the sort order is changed. Or add the sort order to the url as the cache key.

Shouldn't the list be sorted by the user's preference?

Ok, checked that change in. Let's see what the users think about it.