My favorite tube set is TS 5998 and TS 6F8G black glass, round plate. I also like rolling 12AU7 so I use an adapter. Like many others, I experience hum using adapters. I noticed hum was absent at MIN and MAX pot settings. So I decided to experiment with a preamp so I could leave the pot at MAX. I chose to go with an LDR (light dependent resistor) preamp when I came across this kit. It comes in three parts – an LDR board, controller board and potentiometer. All I had to do was just connect these three components and provide 12V power supply.
When I powered it up I was blown away. No more hum and a huge improvement in sound quality across the entire frequency range. Cymbals have more shimmer and bass drums have more attack. Each instrument seems to stand out in its own space. I could go on but suffice to say I am amazed that the Crack and T1 could sound so good with this upgrade.