Headphone amp as pre amp


I'm considering to buy a tube pre amp and a tube power amp. Then I realized that my headphone amp, Feliks Audio Elise, has line out and should work as a pre amp. But what are the draw backs compared buying a pre amp?

Any suggestions of tube power amp, with EL84 or EL34 tubes. It has to be a Push-Pull as my speakers ar at 89dB sensibility. And if you have suggestions of a pre amp too I would be grateful.
Budget is aprox $4500 for both.

What about these Dynaco Latino ST-70? Any good compared to the the real Dynaco ST-70 Series 3?
I use my Benchmark headphone amp as a pre and use clean out to my Mac 275 tube amp with excellent results 
Using a headphone amp as a line preamp should present no problems and could make the circuit work better anyway. Since the load impedance of the headphone is removed for use as a line stage it’s circuit should then work with lower distortion.
For poweramps, try the classic Music Reference RM-10. It’s a powerful little push pull EL84 poweramp offering around 35w, that should drive 89dB speakers to reasonable levels.
It can work well but is one line input sufficient?  

I am currently using a rogue audio RH-5 headphone amp / linestage preamp even though I have no interest in headphones.  It sounds amazing and has (4) inputs.  
The Felixaudio headphone amp sure looks like a fine product. Have no experience with it. Only drawback I can see is that it only has a single input. On the web site you provided I did not find what the output impedance was, which would help in matching it to a amplifier. I would give it a try and purchase an amplifier.