Is pre-amp getting killed?

Hi,
   I'm in the market for the Pre-amp and DAC. I had the PS audio Stellar Gain Cell DAC/Pre-amp combo and I sold that to go separates. I thought of buying PS audio Direct Stream DAC and Audio Research REF 6 Pre-amp. I started doing research and spoke to few dealers. Below are the recommendations I got,

1. Bel Canto EX DAC
2. Simaudio 390 Network Player/DAC

3 dealers I spoke recommended to go with Pre-AMP/DAC/Network player combo instead of separate Pre-amp and DAC. Is pre-amp's are getting killed by the combo? 

Any thoughts?