USB is one of the banes of digital audio. Cheap USB cables contribute considerably to the problem. This technical measurement post will consider one specific, very important attribute of a USB cable, the shield. Shielding functions to keep electromagnetic interference (EMI) out of the USB data signals and to contain the USB data from contributing to the ambient EMI. Consider that USB logic lines have only a couple of volts of Common Mode Rejection (CMR). Light dimmers, small motors (refrigerator), nearby Switch Mode Power Supplies (SMPS), especially the cheap ones, all may contribute to EMI disturbance of USB data if the shield doesn't perform well. To perform well the shield requires a low ohm galvanic connection with the A and B end connectors. 8 USB cables were evaluated for shield resistance to A and B end connectors. 5 - generic, the type usually included a with USB device. 2 - Audioquest Forest, 0.75 meter and 1.5 meters length. 1 - Schiit Pyst. Data were acquired using the following: Keysight 34461A 6.5 digit DMM with Benchvue for data logging APRS World USB A breakout board APRS World USB B breakout board Each cable tested had both A and B ends inserted twice into the breakout boards to assure removal of any oxidation on the shield connection. Each cable was measured over a period of 10 minutes twice, first time to allow for settling of connector materials, the second for measurement of record. Measurement setup: The cables: 1 generic clear small 2 generic black small 3 generic clear large 4 generic black small 5 Audioquest Forest 0.75 meter 6 Audioquest Forest 1.5 meter 7 generic black stiff cable small 8 Schiit Pyst Results (lower resistance in ohms is better): 6.5 to 7.5 ohm range expanded y-axis: I wouldn't trust this cable (#2) to work reliably in printer usage. 2.5 to 3.5 ohm range expanded y-axis: #1 isn't much better than #2 - note the sudden jump - explained below in mechanical disturbances 0 to 1 ohm range expanded y-axis: #3 and #4 are better but still considered failures as they are much higher in resistance and continue to vary over time. #6 and #8 (Forest and Pyst respectively) are both low in R and constant over time. Mechanical disturbances: Look again at the USB cable in the 2.5 to 3.5 ohm range y-axis expansion, near the end at 9.75 min. That sudden jump was coincident with my sneezing approximately 0.5 meter distant from the cable, facing away from the cable. Galvanic resistance is easily disturbed in the cheap USB cables. Better quality USB cables are much more robust. A squeeze test consisting of gently applying pressure both A and B ends approximately 15 cm from the end demonstrates this disturbance. The fit between the USB cable and breakout board connectors is tight. Care was taken to avoid connector to connector movement during this test. Only the shield to cable connector transition is receiving stimulus. Here are some examples. Squeeze test examples: #7 varies considerably and unpredictably with the gentle squeeze test. #8, Pyst both varies little and is repeatable. Conclusion: Audioquest and Schiit know how to specify and build (or have built for them) cables with decent shield connections. USB cables included with USB devices that I've examined thus far appear to be mostly crap.