For "tiziness" address line conditioning, upgrade AC cords, & cabling compatibility issues. However, distortion only at high levels is probably just simply amplifier output-clipping, where the unit is running out of gas.
Insulating an amp in any type of sand, mud, whatever material, is begging for heat related failure. Heat sinks aren't made for their appearance, they actually perform a critical function. And if tubes are in the mix then you're really asking for trouble.
Insulating an amp in any type of sand, mud, whatever material, is begging for heat related failure. Heat sinks aren't made for their appearance, they actually perform a critical function. And if tubes are in the mix then you're really asking for trouble.