Need Help with Hum

I have a Krell 400cx, Krell KPS-25sc, Musical Fidelity Tri-Vista SACD, CAST cables, Von Gaylord Chinchilla ICs, Siltech Power cords, Siltech speaker cables, Rotel power conditioner, JM Lab Mini-Utopia, JM Lab Sub.

The system was working perfectly; not a spec of hum, dead silence.
I installed separate 30 amp and two 20 amp lines for the system, Hubbell outlets, and ran the wires below the floor to the outlets. IT all works but now the system has a faint hum but only when the Krell KPS preamp/CD is on.

Can anyone help me as to a starting point to diagnose the problem?
I am most appreciative. The work was done by an electrician who specializes in these kinds of home-tech installations and will also try to address it but I thought I would also ask all for ideas.
If the components which were once on the same line are now on separate lines, there are at least two issues which might contribute to the problem you have. First, the separate lines, due to line length/configuration, might have slightly different ground potentials. Second, one of the lines, probably the one with the pream/CD on it, is connected close to another line in the box which is throwing out some noise.

Kal (not a licensed electrician)
Float/lift the ground connection on the Krell KPS preamp/CD with a cheater plug and see if the hum goes away.
If does than check the wiring as Kal suggests, if it doesn't, check and make sure the hot & neutral on the AC
line feeding the Krell KPS preamp/CD are not reversed. Most hardware stores sell a inexpensive devices for checking wiring.
I do agree with the above, but also I found that sometimes if your external power cords are laying in a certain position, perhaps too close to a component, or speaker cable or interconnect, that also can cause a hum. Also still keeping your digital and analog seperate , sometimes the order in which the plugs are in the outlets can have an effect. As I said I do not disagree with the above, but Ive had a few hums drive me crazy and this was a solution.
You guys are great. I printed out all your suggestions and will discuss with the electrician. I will only fiddle with wires myself as a last resort. Thank you so much. This is why I love this sport.

Plug everthing into same outlet, hum will go away.
The polarity checker for checking to make sure the wires are correct only costs 5 bucks and you just plug it in, I'd do this to make sure they are right. Besides you can check the other outlets in your house while you're at it. I had a similar issue and it was just that my wiring mess behind my system needed to be better organized.
Two things that might cause your problem...
If the branch circuit home runs are long you may have a ground loop problem. How far would you say they are from the receptacles to the main electrical panel? Try connecting the three equipment grounding conductors together at the receptacle roughin boxes . This will create one common star ground point close to your equipment.
Second problem could be, if I understand you correctly, you had three new dedicated circuits installed. Each with a seperate 20 amp single pole breaker. I am just guessing but I believe the electrician put one circuit on "A" phase L1, Next circuit on "B" phase L2 and the last circuit on L1 or L2. Have the electrician put them all on the same phase. Either L1 or L2, but not both. You could put your power amp, the #10 wire conductor on one 20amp single pole breaker and the other two circuits, the #12 wire conductors on one 20 amp single pole breaker. Just make sure they are both on the same phase. I would try this first before the ground fix.
One thing more, make sure the electrician connected the equipment grounding conductors to the neutral/grounding bar in your main electrical panel. This method is for a house main service panel. The neutral is bonded to ground by the grounding electrode conductor on this bar. All branch circuit neutrals and equipment grounding conductors terminate on this bar.

Hope this will help,Jim