Davt, i have the MSB Analog DAC with the upgraded Power Supply and I like it a LOT! I opted for the volume control too, but really only for re-sell protection. I run the MSB into my tubed Holvland HP-100 pre.
I use a Mac Mini as my music server with an external 3TB hard drive connected via FireWire as my storage device. I use Audirvanna on the Mini as my player. Very happy with this setup.
The MSB Analog DAC is not cheap, but overall I liked its sound better than most of the mega DACs costing much more. I spent some time comparing the Analog DAC to a number of other DACs before makng the purchase. I auditioned the Wyred for Sound, Benchmark, ExoSound, EAR Dacute (my second ranked choice afer the MSB), Ayre Q-9, PS Audio Perfect Wave II, and the Bricasti M1 and a few others I can't remember at the moment.
The Analog DAC is nice and 'smooth', not 'digital' like so many other DACs that I have heard. It produces an exceptionally wide soundstage left-to-right and front to back with excellent layering (when it's all there in the recording of course). Presentation of detail is excellent, highs are very extended but not bright or edgy. It is not a 'detail freak' like the Benchmark for example, but I found it to be much more musical overall; a lot like how musical really good vinyl can be.
I liked the Analog much more with the upgraded power base; a must have in my opinion. In the event that you ever try to sell the Analog used it will probably help to have the volume control, so yes, I would get that added.
Also, the Analog is not a true 'balanced' design so it sounds much better just RCA.
I bought mine last December and would make that purchase again without question. I am pretty sure that that the Analog DAC will be all that I need for the next five years or so...maybe longer.