Anyone had the equipment customized ?

That does make a lot of sense.  Rail to ground decoupling caps work much better at killing noise when they have a moderate amount of ESR in them while DC Blocking caps passing a signal work best when ESR is held to a minimum.  

I’ve upgraded my phono stage with a Burson SV6 Classic and regulated power supply. Soon to modify my integrated amps to bypass the integrated phono stages. 

@spatialking said:

Rail to ground decoupling caps work much better at killing noise when they have a moderate amount of ESR in them while DC Blocking caps passing a signal work best when ESR is held to a minimum.  

That is incorrect. ESR in bypass capacitors reduces their effectiveness. The goal of bypass capacitors is to stabilize Vcc and displace noise to a part of the power bus that has higher impedance than at the point of consumption. It is  the lower impedance in a voltage divider. The lower that impedance is with respect to the upstream part of the supply rail, the more noise is displaced there. 

That is the often thought philosophy.   It is a small amount of ESR, which dissipates the noise energy as heat, rather than dumping onto the ground plane and causing ground bounce.   Sure, a cap with large ESR can cause a spike on the chips power pins, what is needed is a small amount of ESR in a bypass cap to dissipate that spike as heat.     

Some large computer back planes have shunt VHF caps in series with a 1 to 10 Ohm resistor to ground just to keep the power plane resistive and lossy at higher the frequencies where typical bypass caps have gone through their internal self resonance.  

For series DC blocking caps, then, yes I totally agree, the lowest ESR cap is best.   

High ESR means that the terminals of the cap will not present a low impedance to high frequencies. Since bypass caps are in parallel with the Vcc pin on ICs, that means the noise is still present. The only way to displace the noise is to present a much lower impedance than the power rail etc, that is upstream from the point of consumption.