Groove Tubes' highest-gain preamp tube. This tube has a huge amount of gain, with terrific output that makes it a great choice for driving modern, complex high-gain circuits. It has a relatively high quality variance (making Groove Tubes pre-testing procedures especially important in this case), with a tight, strong and relatively bright tone that can really liven up a weak or tired, old vintage amp or a new amp with grade-quality tubes. These pass every Groove Tubes premium certification for micro-phonics, hum, physical characteristics and function. Quite simply the best 9-pin triode preamp tubes you can buy specifically designed and tested for musical instrument amplification and standard equipment on Fender amps. Outstanding and consistent performance for mixing and matching to get a signature tone from your amp. Groove Tubes' highest-gain preamp tube. This tube has a huge amount of gain, with terrific output that makes it a great choice for driving modern, complex high-gain circuits. It has a relatively high quality variance (making Groove Tubes pre-testing procedures especially important in this case), with a tight, strong and relatively bright tone that can really liven up a weak or tired, old vintage amp or a new amp with grade-quality tubes. These pass every Groove Tubes premium certification for micro-phonics, hum, physical characteristics and function. Quite simply the best 9-pin triode preamp tubes you can buy specifically designed and tested for musical instrument amplification and standard equipment on Fender amps. Outstanding and consistent performance for mixing and matching to get a signature tone from your amp.