I have the later incarnation 7.1i and overall, they may not be the best speaker I've heard (I was in the HiFi biz for nearly 30 years) but they're the best sounding speakers I've owned and that includes Altec A7 500's.
If you start to Google search, you will find references about how the Polydome mid ranges change color over time, They start out nearly clear, I bought brand new in 1993/94 ($500 for the pair - a special price from the distributor rep) and at about 5 years milky streaks appeared and they are now a solid pale yellow like yours. apparently this is not something to be alarmed by as long as the material stays pliable and if it does harden - DON"T TOUCH THEM!!!
Like mine, yours may be position sensitive. When I first got them, it took a couple of weeks to dial them in and I was surprised at how much effect just an inch forward/back and a degree or two of toe in/out had on them. Oddly, in the room they were in when I first got them, the best sound was obtained with the right speaker about two inches farther forward from the back wall than the left speaker. Now, I'm not so fussy.
7.1i's use a 10" and ported at the back and a newer generation EMIT. Are yours ported too?
I used to sell Infinity's and the original EMIT's did not give any warning before they blew. They sound real good until it's too late so be careful.
If yours are so equipped, remove the jumper and try bi-wiring them. I thought it made a noticeable difference and I'm not one to pay much heed to the
Tweekophile stuff. Selling HiFi for as long as I did makes you cynical.
This a photo I grabbed online but they're exactly like mine including the milky Polydome.
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EDIT: BTW, I have a WOPLized 700B (thanks to Lee and Jerry) and they've never sounded better.