Try adding large paper/oil caps in series with one of the AC line wires, the type used for running AC motors and compressors, to see if it removes the hum. If does not resolve the problem the toroid could have enough of a magnetic field to excite some nearby ferrous object. Most likely the extremely toroid has shaken loose in shipping and/or is misaligned. Check the center mounting bolt for torque.
If it really is a DC issue, then you could look up some ultraisolation transformer.
I doubt you are using much the 5KVA of the transformer. Check the efficiency rating of your speaker and measure SPL one meter from your speakers and estimate how much power you are actually using. You can also plug in a Killawatt meter from Home Depot and measure power draw. This will help find a rating for an isolation transformer.
As the problem appears with no output very little power is used.
90 dB SPL average is more than my ears can tolerate and with 90dB 1W speakers very little average power is actually used. 20 dB peaks will be at 100W.
Most of the music energy is in the bass, where powered sub does the heavy lifting. Low frequency sounds are mostly non-directional and are mixed to mono on vinyl. So the need for stereo at low frequency is just not there, minimizing large speaker requirements, if you have a sub. This could lead to improved domestic happiness and possibly more flexible speaker placement.
If it really is a DC issue, then you could look up some ultraisolation transformer.
I doubt you are using much the 5KVA of the transformer. Check the efficiency rating of your speaker and measure SPL one meter from your speakers and estimate how much power you are actually using. You can also plug in a Killawatt meter from Home Depot and measure power draw. This will help find a rating for an isolation transformer.
As the problem appears with no output very little power is used.
90 dB SPL average is more than my ears can tolerate and with 90dB 1W speakers very little average power is actually used. 20 dB peaks will be at 100W.
Most of the music energy is in the bass, where powered sub does the heavy lifting. Low frequency sounds are mostly non-directional and are mixed to mono on vinyl. So the need for stereo at low frequency is just not there, minimizing large speaker requirements, if you have a sub. This could lead to improved domestic happiness and possibly more flexible speaker placement.
