The bass on Miracle and Merlins is just different (pure armature bass vs dynamic bass as I hear it IMO), in terms of quantity I think that Miracles have more bass, but it's tough to judge... Miracle is definitely much more neutral on middle and high frequencies and also much more darker in this regions... so overall this two models sound totally different, especially if you pair them with cables that benefits their pros, to my ears it's TWcu3 for Miracles and TWag2 Gold for Merlins, but if I had only one of this CIEM's, then I probably choose different cables pairs (TWcu3 for Merlins.. for Miracles... hmmm... I don't know actually, probably would try TWag3 for Miracle, I think they will be a good much for one and only CIEM, but I don't know what will be in reality though... actually don't really like Miracles with TWag2 Gold at all, it kills all the neutrality in mid and high frequencies, and bass is still no much for Merlins, so this cable is bad choice for Miracles IMO, maybe TWag3 will be also bad with them...)...