The Burson Buffer has not been made for quite a while now, and are hard to find. However Burson has this ingenious RCA cable with a small solid state buffer built into it. It is powered by 5 Volts DC. It will help with most any impedance mismatches.
Impedance Matching Question
Most know that the input impedance of an amp needs to be ~10X the output impedance of the preamp for proper matching. Is there an inexpensive device that can be placed between a higher impedance preamp and lower impedance amp to help solve the issue? This is not for critical listening, but I do want it to sound good.