Is usb reclocking necessary?

With Asynchronous DAC like Ayre QB9 data is not delivered in real time*. Asynchronous means that USB clock and DAC’s D/A conversion clock are independent (asynchronous). Reclocking Asynchronous USB doesn’t make any sense. On the other hand "Reclocker" might have built-in filters on data and power lines that reduce injection of digital noise into DAC (always good thing). I would search for USB filter (but such filter might be already built into DAC).

*Computer sends data in "Frames". Each frame contains multiple music samples. These frames come at slower rate - likely 1kHz.
DAC places them in the data buffer signaling back buffer’s under or overflow. Upon this signal computer adjusts size of next frame.
That way clocks are independent, but data is not lost.

When DAC is self powered, then USB power is not necessary but GND connection is still required since single ended (GND referenced) signaling is used at the start.  It might be possible to lift the GND after music started playing as long as data common mode stays within input range.

@yage Thanks.  In that case I cannot see any reason even for filtering.