Are all asynchronous USB inputs similar?

"Why is it that Top quality USB Converter/re clockers are not typically built into the DAC itself, or why can't it be or maybe why is it that outboard USB converters seem to always be better than an onboard unit? Power supply? "

I'm afraid that its just experience and design skills that are lacking. Most USB interfaces on DACs are either new designs by designers that have never done this before, or they are designs by third-party contractors with more interface experience, but little product experience. Product experience would allow them to select the best clocks and other components, optimize the power supplies and the ground-plane infrastructure in the DAC to achieve really low jitter using USB to I2S.

The built-in USB interface (USB to I2S) on my Overdrive DAC is now actually better than the Off-Ramp 5 with Dynamo power supply that I sell.

Totally uninteresting tracks like "Gimme Shelter" from the Stones Let it Bleed now sound fantastic, with weight, depth, slam and great tonality. I can actually understand most of the lyrics now.

Steve N.
Empirical Audio

In my own experience with the Cambridge Audio DACMagic Plus and the Audioengine D1, USB 2.0 works fine in the office but my home PC is a gaming rig that is *heavily* overclocked (it requires water cooling to remain stable).

In that application, USB 2.0 is unlistenable and I rely on toslink SPDIF from the mobo to get clean audio.

What about I2S directly from the computer to the DAC. I know a company that offers a I2S PCI card with a HDMI style I2S output.

This company also makes DACS with I2S input of course.

Mordante - I2S is not particularly helpful if the clock is still powered by the computer. The main objective is to reduce the jitter of the master clock. The best way to do this is get the Master Clock out of the computer and on its own power system/supply.

Also, S/PDIF can be superior to I2S if it is galvanically isolated from ground returns. I2S and HDMI I2S is very difficult to galvanically isolate. I have both HDMI and RJ-45 I2S outputs on my products. I was the first to put HDMI I2S on my Off-Ramp 5 USB converter.

Steve N.
Empirical Audio