TUBE-TECH SSA2B sums your mixes Wide, Punchy and Transparent, with Rock Solid Low End! The TUBE-TECH SSA 2B Stereo Summing Amplifier features two very low noise/low distortion summing amplifiers with a very wide frequency response. It provides a high end, yet cost effective solution for analog summing, and the simple layout of the SSA 2B makes recall just as easy as when you work ITB.