Help diagnose problem with my amp


I have been using a Myryad SS integrated amp (MI-120, 60 watts/channel) in my system with ProAc D15's for a few years now. I have been plugging the amp into an Ensemble Isolink then to the wall. Last week, the volume has dropped by a quarter of the dial! I checked all connections etc. and nothing appears amiss. It's not just one speaker, both speakers now play at a far softer volume at 9 o'clock on the dial, which previously was plenty loud and detailed. I now have to turn the volume up to 12 o'clock for acceptable listening levels of depth, body and detail. This morning I wondered if somehow the Isolink had begun muting the amp's current, so I unplugged the amp from it and ran the power cord straight to the wall but no change. Any ideas?
sc53
It's possible there's an issue with the power supply voltages. Voltage regulators can fail and/or no longer regulate properly. Voltage may have dropped causing a decrease in gain. Depending on the circuit, that would account for both channels being down in level as they share a common voltage regulator. It's also possible a fuse or resistor in one of the power supply rails has failed. This can also cause a problem with the power supply voltage. If this is a tube unit, a tube that's common to both channels may have failed, usually the input tube.
Again, thanks for the suggestions. This is a SS not tube unit. I have contacted Myryad tech support in UK and hope to hear something from them. I really love this amp so hope I can get it repaired. I have no local stereo repair place and am not sure where I could send it in US.