RME ADI-2 DAC FS is it "All That", especially for under $2,000?

Brad1138, I'm guessing you purchased both DAC's to A/B them? Please let us know if the Topping is on par with the RME at only $ 630-that would be a great value proposition!

I've had the RME for about three years. I find no reason to upgrade. It's extremely flexible. Also if you find the manual a little intimidating go to RME ADI-2 DAC walkthrough. There is a 25 minute step by step video on how to operate the DAC. 

I just received a new RME DAC today, am running it balanced, in bypass mode and it has impressed out of the box, without adjustment. I would be interested to hear suggestions for adjustments.

+ I need to connect 2 Macs, but there is only one USB socket. I am thinking about 2 possibilities. I already have an external USB to SPDIF converter (a Hag USB), so could connect one source via Coax. Alternatively I get a hub, to connect both sources to the one socket. I do not want to degrade the sound and ideally would prefer not to have to switch between the two sources on the hub.
Thoughts?

by the way, The RME feeds into a Pimare P30 pre-amp via balanced connections, in stereo bypass mode (so there is no reconversion to digital). I have active monitors, so everything has volume control.

I think you would want a USB switch instead of a hub. With a switch you can connect multiple computers to  multiple devices a hub you connect 1 computer to multiple devices.