JFD11, have you tried switching from the 8 ohm to 4 ohm taps (or vise-versa) on the VS55? If this doesn't work, I can only believe there is some odd impedence mismatch between speaker and amp, or something else buggered up in your system. My VS55 has been effortlessly driving a pair of Verity Parsifal Encores for 6 years, in a fairly large room. This amp is a winner and so are your speakers, so something's amiss.
