They appear to be made to work with both 1/4-inch posts and with 5/16-inch posts.
Are you sure they do not fit, even at the end where the opening is larger?
AZ can reterminate them if you are not comfortable doing it yourself.
if you want to hear them first, before taking that plunge, buy some inexpensive individual (I.e., not connected pairs) bananas, connect the spades to the bananas and insert the bananas into your binding posts, assuming the posts accept bananas.
Are you sure they do not fit, even at the end where the opening is larger?
AZ can reterminate them if you are not comfortable doing it yourself.
if you want to hear them first, before taking that plunge, buy some inexpensive individual (I.e., not connected pairs) bananas, connect the spades to the bananas and insert the bananas into your binding posts, assuming the posts accept bananas.