Longer is better?

@mitch2   It is the same bit that is affected.  Beginning of transition ("knee") reflection from the end of the cable comes back and affects the shape of the same transition at source.  Reflection comes from any characteristic impedance boundary.  Signal travels at about 5ns/m making total propagation time 2x1.5mx5ns/m=15ns.  Reflection will deform originating transition after midpoint (threshold) since typical transition is approx 25ns (won't affect 12.5ns threshold point).   It is guessing game since transitions can be longer or shorter while signal propagation depends on cable dielectric.  Perhaps 2m would be even safer.

As follows is what AI had to say on the question at hand.  Interesting. 

Shorter USB cables are generally better for connecting a streamer to a DAC in audio setups — they minimize electromagnetic interference (EMI/RFI pickup), voltage drop (especially if bus-powered), and overall signal risks.

•  Longer cables increase potential problems — more chance of noise, power issues, or even dropouts beyond ~5m (USB spec limit), with no real benefits in typical modern asynchronous DACs.

•  The “reflections” argument for longer cables comes from a niche audiophile claim: very short cables (<1–1.5m in some old discussions) might not let signal reflections (from impedance mismatches) decay fully before the next data bit, potentially worsening jitter in poorly matched systems.

•  In practice, this claim is weak and not widely supported — modern asynchronous USB DACs reclock and buffer data with their own precise clock, largely eliminating cable-induced jitter/reflection effects; measurements (e.g., Audio Science Review, Archimago) show no audible/measurable audio differences from cable length variations when the link is stable.

•  Consensus from engineering & objective tests — shorter, well-made, properly shielded USB cables (0.5–2m) are reliably better or neutral; deliberately going longer to “fix reflections” is mostly cable-marketing hype, not physics-backed evidence.

•  Bottom line — Your retailer is likely stretching (or inventing) a reason to sell a longer/premium cable. Stick with a short, quality one for best results.

Sleezaball. Minimizing signal path is better, within reason. Use your best judgement

That’s what she said

Did you ask him why he said that?