The problem with quick A/B comparison - especially if you don't know the headphones well - often lies in:
- improper volume matching
- unfamiliarity with a headphones signature.
If you don't volume match both headphones - the one that is slightly louder will often be perceived as better. So in this case - if you have the buds volume louder than the fsp - they may sound similar to you, when in fact there is a world of difference. The only way to accurately match is with an SPL meter and test tones.
And secondly, if you rapidly A/B two headphones without spending enough time with each, it's often very hard to really understand SQ differences. Your brain needs time to 'acclimatise' to the new sound signature. If you are used to the buds, but not used to the fsp, then switch rapidly between both - you may find you prefer the SQ of the buds as that is what you're used to. My advice - wear the fsp for a couple of days - then switch to the buds, and see if you then notice a bigger difference. Often it's more apparent once our ears/brain have adjusted.
Hope this helps.
This is sound advice (!)
Seriously, once you become acclimatised to a superior product, there is no way to go back.
It's a bit like watching SD TV. When it was the best we could get it was great, but after watching HD, it looks shi rubbish and there is no way to go back. Cream floats to the top.