The stock of LL Flooring Holdings Inc. LL rallied 21% in premarket trade Wednesday, after the company confirmed it has received an unsolicited but non-binding bid from Cabinets to Go, a unit of F9 Brands Inc. F9Brands owns and manages a portfolio of companies in the building products, home improvement and luxury home décor industries. The flooring retailer, formerly known as Lumber Liquidators, said its board will consult with financial and legal advisers to review the bid. The company believes its long-term fundamentals are strong and it’s succeeding with six core growth strategies. “LL Flooring believes that it is…