Hum issue with the Gryphon Legato Legacy

Feb 26, 2016
I posted this in the Gryphon forum but did not get any response. Hopefully will have better luck here.

I received my Legato Legacy early last week and while the sound has been great I've been afflicted with a strange hum problem which after extensive troubleshooting is caused by the Legato Legacy's phono picking up noise from it's power supply. First some details of my setup. I have two 4 tier hifi racks set up side by side. If you are standing in front and looking at my system, on the left hand side rack, top shelf is my CD player while bottom shelf is my Gryphon Diablo 300 int. amp. I removed the shelf immediately on top of my amp for better cooling so this means the left 4-tier rack is now only 3 tier. On the right hand side rack, top shelf is taken up by my Kronos Sparta turntable while bottom shelf was initially taken up by my Entreq ground box.

Upon first install the Gryphon Legato Legacy's phono was placed on the rack underneath my CD player (left hand side rack) while the Legato Legacy's power supply was on the same tier/level but on the other (right hand side) rack underneath the turntable. With this setup the hum was audible from my listening position. After extensive grounding/ground loop troubleshooting which also included replacing both the Legato Legacy and its power supply with the ones from my dealer we are 100% sure the problem is caused by the phono picking up noise from the power supply. I do not have any hum with the power supply on the floor behind my hi-fi rack but this location is not convenient long term as the power supply is now sitting in from of my staircase. Finally I moved the phono to the right hand side rack bottom tier/shelf while the power supply was relocated to the left hand side rack tier beneath the CD player. With this the hum was reduced by 90% and now only audible when I put my ears close to the speaker.

My questions are whether the Legato Legacy is designed for side by side placement and should I relocate it to the same rack (both phono and power supply on the same rack but different shelves) to eliminate the last 10% of the hum? The Legato Legacy is on the same shelf different tier at my dealers and is dead queit there. Would appreciate thoughts and advice from fellow Gryphonistas, dealers, etc familiar with the Legato Legacy.

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