According to the American Heritage Dictionary, both pronunciations ('konk',
plural 'konks', and 'konch', plural 'konches') are valid.  But because the
word comes from the greek stem pronounced 'konk' (definitely no 'soft'
pronunciation possible), I think among 'konkologists' (her we can't have
'soft', even according to the AHD) the 'k' pronunciation is preferred.