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I read somewhere (maybe here) that the mesh is different and that it wouldn't give you the same user experience if you used old ones. Sound a bit weak and more of an excuse to sell more eartips.

So I thought it was BS too. I tried my APP 1 silicone tips on my APP 2 and it did make a difference. However, the comply tips on both gen 1 and 2 didnt make a difference too me.

I think its also based on the music you listen to. I listen to a lot of sub bass heavy music so when I heard vocals / highs, I could tell a difference between the tips but otherwise I couldnt really besides the APP2 having a lot better bass / mid response than the APP1's
 
Hopefully of intertest to others; I bought a pair of 1st gen APPs last year, but found them dreafully uncomfortable, after just 5 minutes. I was using the smallest ear tips. I sold them on at no loss. I took a gamble on the 2nd gen versions, because of the new XS eartips. They were better, but still uncomfortable for prolonged use. I bought some (very expensive!) Azla Sedna Earfit Xelastec eartips in size 'SS', and these have been much, much better. No longer suffer discomfort. They seal well and don't seem to affect the sound in any way. So perhaps that info could be helpful to others suffering similar problems.
 
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