To much high

This weekend I traded my B&W CDM1's for a pair of beautifully finished home-made speakers, comprising a Morel tweeter, Seas (aluminium) mid/low and Seas woofer in a tall housing. I listened to them on a tube amp in a heavily furnished room, and they sounded awesome. Back home (you guessed it....) I connected them to my transistor amp, in a rather hard-sounding room. The low and mid is everything I ever dreamed of, but the top-end is driving me nuts. Since I don't have the cash to change my amp I'm thinking of changing my (silver) speaker cable, or, as some sort of last resort, placing a resistor before the tweeter. Any (other) suggestions?