Headphones

I've bought the same exact iems and the sound is completely different. Second set isn't as loud and the same Bluetooth adapter is worse as well. Moved out of an apartment and left most of my shit there. My iems being a part of that. Ordered the same exact ones along with the same Bluetooth adapter and quality is worse and when using the phone for calls people can barely hear me. My first set was perfectly fine and never had any audio issues on the phone. Not everything is made the same even if it's the same exact product.