How essential is shielding?

"What are your thoughts on (Synergistic´s) active shielded cables?"

Very high tech and very expensive.

I'd have to hear them to make any value judgement.

Personally, I prefer an effective shielding approach that is not active, like mu metal, which I already use to good effect to shield my phono step-up device and ICs from external noise inducing EM fields.

FWIW my Audioquest CV6 speaker wires use a similar but lower tech and cost active approach with their DBS devices. These speaker wires are very good but I have not been able to determine how much DBS has to do with it.

Of course, low level ICs and speaker wires are two different beasts as well to start with.

I have found it can make a difference in noise levels in some cases and not in others.

You have to experiment to determine.

Orientation and position relative to other wires with current passing through or powered devices with transformers that emit EM fields matters a lot.

"It is worth to mention that EMI pickup of lower frequencies such as approx 500kHz generated by many class D amps can be picked-up as direct connection thru capacitance (important to keep wires apart or right angle) and not thru the electromagnetic pickup"

I wonder if this accounts for the intermittent low level high pitched whine I get on occasion with DNM Reson ICs from ARC tube pre-amp to BC ref1000ms? The pitch seems to change with exact location/orientation of the ICs. Not sure if position of the two ICs relative to each other is the determining factor or not.

I switched in a pair of MIT ICs with network boxes the other day and that appears to have eliminated the noise issue for now. I'm waiting to see if it continues in that the issue has come and gone mysteriously in the past for no clear reason.

The DNM reson IC configuration strongly resemble 300 ohm twin lead antenna wires. Wouldn't surprise me if they can act like antenna and pick up certain RF noise emitted by the amps perhaps. The nise exists with amps on and pre-amp off and resembles multipath noise one often picks up with FM stereo tuners. Probably not EM the more I think about it, though the buzz in the phono step up rig I eliminated with mu-metal was.