I need to buy a complete system.

Maggie 3.7i, 20.7 depending...
- drive them with a Benchmark AH2B amp (which can be returned!)

used ARC LS25 or 26 pre-amp

Benchmark DAC3 (or Schiit Yggy if Redbook only) (both can be returned!)

investigate an LPS for the Mac Mini (inexpensive)

isolation transformer for a few hundred $$

use the money I saved you on room treatments...

mhsmith,

     I like randy-11's system suggestion but I'd add the Swarm Distributed Bass System for good. natural and solid bass performance throughout your large space: www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/
     You can then setup the Magnepan 3.7i or 20.7 speakers for optimum mid-range, treble and sound stage performance at your chosen seated listening position.  You'd still have plenty left for room treatments to dial things in . This could be a dream system that I'd love to hear.

Best wishes,
   Tim

I assembled a $20k tube/computer audio/TT sytem at the beginning of this year and could not be happier with the results. See my previous post for system details:

https://forum.audiogon.com/discussions/second-system-that-sounds-and-looks-spectacular-i-am-there

Harbeth M40.2 speakers.
The forthcoming DPSpeaker X4 preamp/DAC/room eq
Any beefy 300+ watt power amp
Oppo 203 disc player + nice tv screen to watch opera etc
room treatment to minimize reflections
upgrade potential: multiple large subs

The reason I suggested the Harbeth M40.2 and not my personal favourites the Quad electrostats is that by the description this is for a very large room where the Quads would struggle.
For a review of the M40.2: http://www.theabsolutesound.com/articles/harbeth-monitor-402-loudspeaker/
A lot of amplifier power would be a good idea in this case. Alan Shaw, Harbeth’s designer, recently demonstrated the M40.1 in the Netherlands and the power meters on the demo amp indicated more than 500 watt per channel. Fortunately watts do not have to cost much if you use pro audio amps rather than fancy overpriced high end hifi. A good example would be the Yamaha pxx00 series. See here for a test of the 2x350 watt rms P3500s that until recently sold for about $500 and performed better than some boutique amps costing ten times as much: http://www.homecinema-fr.com/forum/amplificateurs-de-puissance-haute-fidelite/mesures-ampli-yamaha-p... I bought the 2x250 watt P2500s for my son and the sound quality is perfect. Alan Shaw has long argued that Harbeth speakers will perform perfectly with any properly designed amplifier. He has also argued repeatedly that you do not need fancy expensive cables. If you think you need them, your system has a problem.