Have you considered what the combined impedance of the speakers amount to? It may constitute a very low impedance load; a transistor amp will attempt to double its output when the impedance is halved.For example my CJ 350 barely gets warm driving my 8 ohm Spendors but gets quite hot driving the GamuT
L5s which go down to 2 ohms. Or the bias could be turned too high or it could be normal.
L5s which go down to 2 ohms. Or the bias could be turned too high or it could be normal.