Enchantment DC:
10 Base
18 Charisma (42 Unbuffed, +2 Ship Buff, +2 Yugo Pot)
06 Spell Level (Metamagic Feat : Heighten means all spells are cast at highest possible spell level)
02 Greater Enchantment Focus item (Epic Elder's Cap)
02 Capstone : Bard (Enhancement)
01 Past Life: Bardic Dilettante (Feat)
01 Spell Focus: Enchantment (Feat)
01 Spellsong Trance (Song)
=DC 41 Enchantment Spells (Crushing Despair, Hold Monster, Dancing Ball, etc.)
Spell Penetration
20 Base, Caster Level 20
03 Greater Spell Penetration VI Item (Crafted Off-Hander, Greater Spell Pen VI of Major Healing Lore)
02 Capstone : Bard (Enhancement)
02 Spell Penetration (Feat)
02 Spell Penetration II (Enhancements)
01 Song of Arcane Heightening (Increases Caster Level by 1)
=+30 to overcome the Spell Resistance of enemy creatures.
So.. yeah. That's how the numbers break down.
My reference builds are
HERE, Hobadash is the first post. It's pretty barebones - starting stats, feats, enhancements. MyDDO can tell you a little more about my standard equipment, although certain items are swappable.