Toulouse, the inaugural winners, went on a try rampage as they posted the highest-ever score in four years of the tournament against last season's Welsh Cup runners-up Ebbw Vale, running out 108-16 victors.
Ebbw Vale, who already hold the record for the biggest defeat in the European Conference two years ago when they went down 93-7 at Agen, conceded 16 tries.
Leinster became the first side to beat Llanelli at Stradey Park in the tournament and Ireland's other representatives, Ulster and Munster, both won at home.
A try by Gordon Darcy three minutes from time earned Leinster an historic 33-27 win as they condemned the Scarlets to their first home defeat in three years in the Cup.
The French champions, Stade Francais, are favourites to win the cup but they will have to avoid going to sleep in the second half after their 39-28 debut win in the tournament at Begles-Bordeaux.
Having done all the hard work in first-half, when they scored four tries to lead 32-9, they leaked three in the second half and only managed to add one more to their total.Reuse content