Here is a Stereo Tube Preamplifier Kit that is easy to build, and is just fun! The Tube Preamplifier utilizes a 5670 triode. The Preamplifier is compatible with all "L" Series Amplifiers, it gets its B+ and filament voltage from the Amplifier board and can provide 10 to 30 db of gain.
The PL Stereo Tube Preamplifier comes in kit form (K-PL). The kit comes complete with all the resistors, capacitors, tube, circuit board, and necessary hardware for mounting on a "bread board" provided (which is compatible with the amp you purchase or have previously purchased).
Model PL Stereo Tube Preamplifier
Input Impedance = 100k ohms
Frequency Response = 20 to 20,000 Hz
Input output connections = Jumpers to Amplifier PC Board
Gain = 10 to 30 db - set by a resistor
Please Note:  This item is subject to a shipping surcharge.
ALSO NOTE: This preamplifier / tone control kit is not a "stand alone" kit. This preamplifier / tone control kit must be connected to the appropriate amplifier kit for proper operation. This preamplifier / tone control kit will NOT function without these connections. Additionally, because this preamplifier / tone control kit does NOT provide the necessary RIAA tone shaping curves needed for turntable use, this preamplifier / tone control kit is NOT suitable to amplify the audio signals directly from most phonographs or turntables.