Weiss Dac2/Minerva?

You could go with a Weiss AFI1 between the computer and the Alpha Dac.

I have EMM SE separates and Minerva. One for SACD the other for hires and uncompressed dedicated music server.
In my opinion the Weiss is a better bet because of the interface. Shoe-horning low-jitter and hires into USB is tough and fundamentally limited in terms of bandwidth. It has taken a lot of expensive and complex technology for Wavelength DCS and others to make this work reasonably well. Firewire was designed as a networking protocol for media flow: audio and video. It is a better platform now and in the future. The Weiss, in particular, provides a huge amount of input and output flexibility (unlike Linn DS series) plus a great DAC, if not 'world class' whatever that is.

PNCD, can you give us a sound quality comparison of the EMM dac (non SACD) and the Weiss?

I can't to be honest. I understand that these forums are full of golden-eared critiques of various components and combinations, but I do not work that way.
Both are very good. Listening to CDs ripped to FLAC through Minerva I do not miss the CD played through the EMM combination. HiRes sounds superb through Minerva, just as good SACDs sound through EMM.
My point to you was that the Minerva offers a very good package of qualities: digital in and out plus analog, including Firewire and HiRes. Not preventing you from using a different DAC later. It is very good and the support from Daniel has been superb.

About a month ago, I got a home demo of the Minerva, fed from my IMac running the Apple OS & iTunes.

Frankly, I was disappointed.

The sound did not match that of my CD player, which is nothing esoteric... an Electrocompaniet EC-1 Upsampling... :-(