It’s definitely not the SMPS. Any EMI that could possibly be radiating from it are mitigated by shielding and distance. Also I did not build the SMPS. I built a PSU that uses an SMPS, which is an off the shelf component. The parts around it that I built involve the filtering and regulators. The regulators themselves are attached to heat sinks plus in this scenario only one pedal is connected to each regulator. The 12V regulator can handle up to 1.5A and the H90 draws 500mA at 12V. Same rating for the 9V regulator and the UltraTap draws less then 200mA. So regulators themselves are not being overworked.

The power supply that comes with both the H90 and the UltraTap are switching power supplies as well as a vast and great multitude of other digital gear in both the pro audio and instrument markets. Pretty much every piece of digital gear that has the PSU inside is using an SMPS. There may be some devices that are sensitive to these devices but those instances nowadays are somewhat rare.

Again, just for clarification, the following equations are tested to be true with the PSU being used:

PSU + H90 = No Noise

PSU + UltraTap = No Noise

PSU + UltraTap + H90 = Noise

PSU + H90 + Source Audio Nemesis = No Noise.

PSU + H90 + Audio Connected = Wallwart (SMPS) + UltraTap + Audio Connected = No Noise

The problem points strongly to the UltraTap having a flaw of some sort with the DC connection. I just don’t know if it’s with this particular unit or if this occurs when using other pedals in this same series sharing a pedal board power supply with other pedals.

Thanks!

Paul