Here are a couple. The 2nd thread was a few months ago I spoke of (This is a good thread comparing the two). Just search Krell 400xi integrated amp or s300i and you should find plenty of threads :)
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1156724388&read&keyw&zzkrell+400xi
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1230994711&read&keyw&zzkrell+400xi+integrated+amp
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1156724388&read&keyw&zzkrell+400xi
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1230994711&read&keyw&zzkrell+400xi+integrated+amp