As far as I know, you can't put gigastudio in a RACK.

Baltantong, the products you are asking to compare are VERY VERY different animals. The K2600 is a workstation / workhorse. It has incredible sonic generation, synthesis and sorts of whistles and bells (of course, at a price)

The Virtuoso is basically a sound module with voices leaning mostly in the Orchestral range. It has some nifty features, but does not have expandibility like the K2600.

So, to help you decide, what features do you need? The E-Mu is roughly $800, the Kurzweil is on manufacturer special for $2600 right now. The Kurzweil is more powerful and more expandable. The E-Mu has a smaller learning curve. In the end, you should listen to both. If you have the need of a workstation, you can't go wrong with the Kurzweil, if you only need an orchestra sound module, the E-Mu probably would suffice. Besides, for the price of a 2600R, you could get 3 E-Mu's and have some money left over...taking your polyphony to 384!