[Wink]

I happened to snag a set of 63V/10,000ufd FK BG caps for my monoblock
PSUs. The rail voltage with stock Hafler xmfr is ~ 63 Volts so to
avoid exploding my $$ BGs, I'm using a Variac to reduce the AC mains
input for a rail Voltage of ~ 53 volts until I replace the Hafler
trafos with lower sec V Toroidals. [Refer to "Hafler Monoblock
Project..." thread]

The mystery is the sound, which is sort of peculiar. Hard to explain,
but what is the source? Of course there are 3 variables that have been
changed: PSU caps from Chemicons to BGs, lower rail voltage (well
within the operating range of the PA-3D driver board), and inclusion
of the Variac twixt house mains and both amps.

Should I expect some odd interaction between the Variac and existing
Hafler power xfmr? Nothing obvious comes to mind. Running stone cold,
the 1500VA, Powerstat Variac has plenty of capacity.

Not much to go on here, but thought I would throw this one out to you
guys. Thanks again...
Dave