1) This quest, which starts with Melody Maestro Kantabilon in the Grocery at Heine, can theoretically be picked up at level 38. But since the target monsters have really nasty nukes
I would strongly recommend that you wait until you are level 40 and can wear C-Grade jewelry.
2) Kantabilon has found the musical score for a wedding march. Now he needs empty Silver Crystals (50 of them) to store the music. When you agree to get the Crystals
for him, he will tell you to hunt Lienriks and Lienrik Lads. This means that you can - if you are level 39 or above -
combine this quest with "Help Rood Raise a New Pet!" from the Pet Manager on the main plaza in Heine.
3) Lienriks (lvl 39, passive) and Lienrik Lads (lvl 40, aggressive) can be found in the
Field of Silence, some way north of Heine.
There are two subspecies of each, with different kinds of nukes: relatively harmless ice bolts and magic attacks from the normal Lienriks,
nasty fire balls from the stronger Lienrik Lads and poison from the weaker Lienrik Lads. For the latter you will need Greater Antidote. And bring enough
Healing Potions. Those flying snakes are all half HP, but there are a lot of them and they are all social with each other. The quest item acquisition rate is
very bad, only 1 Crystal for every 15 or 20 killed mobs.
4) When you have 50 Silver Crystals, return to Kantabilon. He will give you 25 Echo Crystals with the traditional wedding march. Enjoy.
If you try to sell the Echo Crystals in a shop you will get nothing for them. So do this quest only if you really plan on holding a wedding.
Otherwise it's absolutely not worth the expenditure in Shots, Antidote and Healing Potions.