After looking for a USB filter and failing to find one, I decided to make my own. The screenshots show that the filter improves the noise floor by 8dB on a common USB spectrum analyser, this can also work to improve the quality of USB powered audio equipment such as SDR radios and audio DACs and ADCs.
The filtering capacitor fitted is a good quality low ESR AVX Tantalum TPSE337K006R0100, 330uF, +/- 10%.
Measured capacitance approximately 370uF, USB lead & connector resistance approximately 0.1 Ohm, makes this effective to damp noise frequencies above approximately 4kHz.I can't guarantee this will solve your noise problem as noise can have many different causes, but cleaning up power supplies is usually the first place to start.
For even greater filtering, you could create a pi filter - place one of these filters at each end of your usb extender cable, one at the source and one at the receiver. N.B. Depending on what device you're powering, if you do this you may need to buy a separate USB A to USB mini/micro adapter of the type needed by the powered device. (These adapters are readily available on eBay).