Re: Comfort and stability - QuietComfort and Sport Earbuds
FYI - Many people enjoy the comfort and alternative foam type tips available from Comply. I called support and they plan on engineering and producing a set to fit Bose QC earbuds sometime in 2021.
I use them for other earbuds. The pro is that they increase the passive NC produced, provided a more sure fit in the ear canal and can improve sound (especially bass) quality. The negative is that they feel like earplugs (because they are) and put more pressure in the ear canal. It's a personal preference as to whether or not you like your earbuds supported by something inside your ear canal or more supported by the external ear.