Check the listing for details. TK Audio SP502 500 Series Preamp. Condition: New. Listed at 899.00 USD. Vintage and Modern Tones in One Convenient Package The SPL502 500 Series Preamp from Swedish company TK Audio delivers huge tones that belay its diminutive lunchbox size. It features a transformerless input stage that yields a clean and transparent sound upfront while allowing you to color your output with one of two selectable stages. There’s a Class A-style output stage that sounds beefier, with loads of low-range to midrange punch evocative of the early ’70s British sound. Or, there’s a cleaner output stage for crafting more modern tones from the ’80s, ’90s, and beyond. Sweetwater studio engineers have found the SP502’s DI mode, coupled with the Class A-style output stage, is perfect for recording bass and that its sweepable HPF lets you sculpt your low end even further.