One more thing....the adapter you saw in the store but it didn't say what it was for.....I had the same issue as you when I bought my first sander.....I picked one of those adapters up thinking it would solve my issue (that is if we are talking the same one....it's hard plastic and somewhat bell shaped..)..turns out it is for attaching a 27mm hose to a 36 mm hose.......that's a long hose....lol....then again when up on a ladder on the outside of a house sanding siding it's great to be able to start off with the 36mm and attach the 27 mm.......having said that, the adapter fits perfectly on my Kreg K4 dust port and allows me to attach my 36 mm hose from my boom arm to my Kreg jig......
I guess what most people will tell you is once you get involved in this stuff you end up with a box of assorted adapters couplings, plumbing couplings..heck I've even used old pill bottles....to cobble up to some tools ect.....once you succumb to the fact there are very little standards with a lot of tool companies...you"ll be happy you have a box of all these things so when you come up against a dust collection issue you have enough stuff to make it work....lol
Also since you are using non anti static, you might look at Bosch hoses...I have a 36mm bosch hose...i think they call it 35mm....I use it on my cutting table and it works just fine...bought it from amazon and i think it was 30-40 bucks.....not sure but they might sell a 27mm hose, you'd have to check but for little money you'd have the other size hose.....I think if it were me though I'd get the anti static Festool hose for sanding as you have the extractor and can take advantage of not getting zapped....lol
Greg.