Some of the in-ear models we carry here at Inner Sanctum Audio come supplied with three different sized silicone ear-tips. Some come with up to eight different tips. And there is a very important reason why! When it comes to in-ear headphones, getting a proper fit and seal is vital in order to get great sound, particularly in the bass response. Don't be be too quick in deciding, "These don't sound very good." Try all of the supplied tips. (And if none of them seems quite right, try out some Comply foam tips. These after-market accessory tips are available in three sizes and a variety of shapes. Coming soon to Inner Sanctum. They provide great comfort and isolation.)
Everyone's ear canals are unique. The tips that fit me may not be right for you. Similarly, the tips supplied by different manufacturers are different from each other. For one brand, you may be a size medium, but in another you might be a size large. Even a seasoned audio-head like me can forget that it can truly pay huge dividends to give all of the tips a try. During a recent audition of a much-hyped new set of earphones, I went straight to my default size medium tips, listened to a few tracks and decided, "Meh, what's all the fuss about? These are mediocre at best, with next to no bass."
The missing bass reminded me it might be the tips, so I began swapping them out. I know you can see this coming, so I'll spare you the tedious procedural... Found the right tips and these things at once sounded spectacular - like a completely different product. So there you have it. Take the time and maximize your listening pleasure!