Best Preamp = No Preamp?

I'm currently looking for some DACs. I'm looking at Benchmark DAC1, Bel Canto DAC3, Slim Devices Transporter, etc...

I noticed most of these newest high performance DACs have built in volume control with remote.

I'm thinking that I can connect these DACs directly to my Power Amp skipping preamp.

Is that right thinking? Why go through additional peice of device when I can avoid? Anybody doing it that way?

What'll be the pros and cons?