I haven't flown in J on the LAX <> JFK 321T since last year, but I was disappointed that they didn't give out the headsets in either direction. Just the cheap crappo earbuds.
The headphones were given out in both directions on my onward TATL flights, though.
If it was me, I would hope for the best but plan for the worst by bringing earplugs (sleep through the domestic leg). I wouldn't lug headphones all over Europe on the off chance that the headsets might not be given out.