either you are not ready for this much of details and you expected some thing else , or may be its broken or fake , it dont have big bass , but it has a full bodied mid and highs are good too . consult with the seller or shure , have you tried different ear tips ? and shures are over priced for the performance except srh440 . there are better ones with lower price and some of them are dba-2 , gr01 but vsonic gr07 will do it for you , cuz i think dynamic drivers suits you best .

Either your fit is completely wrong, or you got a dud. The 425's are slightly mid forward - but also quite nicely detailed, and the last thing I would call them is muddy. They are not bassy iems - the 425's never were - in fact of all the xx5 series I'd say they are probably the most neutral.