@dougthebiker Hi Doug, This is what the manufacturer says and to be honest clocking the Etherregen alone, I doubt is going to produce such a big change as clocking your streamer and/or DAC together with the Etherregen.
Extreme usage with an External Reference Clock:
The Crystek CCHD-575 oscillator used in the EtherREGEN is one of the lowest phase-noise production crystal oscillators (XO) available. [Sorry, but the $50~$100 OCXOs we see tossed into stock switches do not outperform the Crystek at low-offsets where it counts; Manufacturers have to spend $500 and up to obtain OCXO clocks with significantly lower phase-noise than the Crystek we use.]
Yet some audiophiles have discovered benefits using expensive ultra-low-jitter/low-phase-noise 10MHz reference clocks with their DACs or USB streamers and conditioners. A clock synthesizer (to generate the various frequencies) is always required for a device to accept an external reference clock. Since we already utilize a very advanced one to produce the 4 clock lines in the EtherREGEN, it was easy for us to include provision for connection of an external 10MHz clock. The BNC jack and termination resistor of the EtherREGEN are for a 75ohm clock line. (We can provide units with 50ohm, but only upon special request.)