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

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.

thanks. yes, i should have said a USB switch. presumably any of reasonable quality should suffice?

Yes, I thought about that, but for the extra there is some flexibility for room correction etc. I´ll get round to that once I´ve figured out the basics. And it´s German, for what it´s worth.

Although it sounds incredibly clear, when the volume is set in mid-range there is more audible white noise from the monitors, more than with the old DAC which is inside the pre-amp. Is there any reason why I should not set the volume to maximum and attentuate through the pre-amp?