The beta 50 uses a film cap to cross the tweeter over, the il 40 uses an electrolytic cap to cross the tweeter over, that will be the only difference in their crossovers, the il 40's tweeter is a little dull sounding compared to the beta 50, if you replace the cap in the crossover on the il 40 with the same brand cap the beta 50 uses (bennic PMT 6.8 uf) they will sound very close.
Infinity Interlude towers...non powered....
Debating picking up a pair of IL 30/40 for second system...familiar with beta series...are these on par soncially?