High-AOV financing, Affirm vs Klarna vs Sweetwater Card vs Splitit?

At $500, $50k AOV financing is mandatory, not optional. 35-55% of conversions touch a financing offer in my data. The four real options:

• Affirm, US-dominant, soft-credit-pull pre-qualification on PDP so the customer sees “as low as $99/mo” before add-to-cart. APRs 0-36% based on credit; you eat a 4-6% merchant discount rate (MDR) on financed orders. Best fit: $500, $10k purchases. Native Magento module.
• Klarna, EU + UK + AU dominant, also growing US. Pay-in-4 (interest-free, 4 biweekly payments) is the default; longer-term financing also available. 3.29-4.99% + $0.30 MDR. Best fit: $200, $3k purchases. Magento module + checkout widget.
• Sweetwater Card (Synchrony), you can’t use the literal Sweetwater Card, but you can offer the same shape via Synchrony Financing directly: 0% APR for 6 / 12 / 24 / 36 months on qualifying purchases. Higher conversion than Affirm on $1k+ guitars because the marketing math is “0% APR” rather than “9% APR.” ~5-9% MDR. Magento integration via Synchrony API.
• Splitit, uses the customer’s existing credit card, no new credit application. Splits payment across 3-24 installments on the existing card limit. Lower friction (no soft-pull), but limited to customers with available credit. ~1.5-2% MDR. Best fit: $1k, $15k purchases for customers who already have credit headroom.

Pattern I default to: Affirm + Klarna + Synchrony 0% APR wired in parallel at checkout, customer picks. Soft-pull pre-qualification on PDP is the single highest-leverage conversion lift on musical instrument stores, it cuts the “is this even possible?” doubt before the customer hits the cart page.