Best pre-amp in an integrated

The reason I ask about the DAC+Power Combo Option rather than integrated+DAC (Rogue Sphinx + Schiit Bifrost) is also because I see things like this on Music Direct:

MUSICAL FIDELITY M1PWR PAIR MONOBLOCKS + MUSICAL FIDELITY M1 S DAC for $1200 down from $4100.

http://www.musicdirect.com/p-263176-musical-fidelity-m1pwr-pair-m1-s-dac-black.aspx

Fortunately/Unfortunately there are very many good products and combinations in your price range

The other variable here is how loud you typically listen to music and the size of your room.

I also agree, pick the speakers that you like best and build around them because there are so many variables in speakers that picking the amp first leaves too many choices.

You also mentioned the possibility of high efficiency speakers. They go best with very low powered tube amps, IMHO, mostly SETs. Personally, I think that is the best sounding combination of all, and will completely blow you away (hence my username). You would be extremely surprised at how loud 2-3 wpc can be with the right speakers. If it were me, I'd go for a 45 or 2A3 amp, some high efficiency speakers and separate DAC.

Given that you are developing your 1st system, have a budget of ~$2000 for an integrated amp and DAC, may move into separates in the future, it my opinion (what I would do, have done) would be to:

1st identify the speakers that meet your priorities regarding sonic characteristic preferences and will attain the loudness levels you require in the room within to be used. This requires listening to many which will help you know (learn ) what sonic characteristics you most desire.. I would think that given your budget for amp/DAC you should listen to those that fall into the $1500-$2500 range. You need not buy them prior to purchasing the amp but knowing what speakers you will be driving helps greatly in selection of the best amplifier. A speaker with 87-90 dB sensitivity, 4ohm+ across the frequency range, with a benign phase angle character would work well with most integrateds having 50wpc into 8 and 100wpc into 4 ohm loads.

Look for a used integrated amplifier (~ 5 years old or so) that mates well with your speaker selection. Help could be sought here. Budget ~$1000-$1500.

Buy a DAC that meets your need for source files. The Bitfrost with Uber upgrade and Gen2 USB comes highly recommended by many AudioGoners. There are many others in the ~$500 range. Differences between DAC will have less impact on the sonic signature of a system than that of speakers or amp.

Buy all cables used.

Again, good luck in your quest.