Having reviewed the Helix, Focus/Focus SE and Whisper for Dagogo.com I have some familiarity with the brand. :)
I have used the Whisper in reviewing with a large assortment of amps including but not limited to Jeff Rowland class D, VAC Phi 200, Pass XA160.5, Pathos Classic One MkIII (two units in Mono mode; currently for sale), Cambridge Audio Azur 840W, and Wells Audio Akasha and Innamorata, etc. All of these have been reviewed; if you wish to see the character of them you can read the reviews. I have done two write ups of the Whisper which you may enjoy at Dagogo.com.
I am not hard core HT, but listen to stereo about 98%+ of the time, so my comments on setup are to be weighted. I do use different amplification for the surround system; I also use the Magnepan MGMW for the Mid and Rear surrounds. So, I do not have absolute consistency with surrounds in either amp or speakers. However, I watch a movie perhaps once a month, if that. I put the bulk of my money into the two channel experience.
If HT is critical to you I would strongly consider similar brand for all amplification, as the amps do carry a sonic signature and house sound. I would put the bulk of the money on the two channel amp and quite a bit less on the surrounds. The center I would put a good amp on since the nature of the human voice changes dramatically with a good center/amp.
The advice regarding the efficiency of Legacy speakers is true. I have used all kinds of amps with the Focus, Whisper, etc. If you go with tubes you may encounter a lot of tubes throwing off a lot of heat and longer term maintenance costs. Solid state would give you less issues potentially of biasing, tube replacement, etc. I have put together many systems with a tube amp, i.e. VAC, up front with the mains and solid state with all the rest. My perspective on this may conflict with some ardent HT fans, but once the system is set up and you get accustomed to the sound it becomes "natural" to your ears. I am quite sure the surround could be vastly improved, but with budget considerations and emphasis on the mains I am content with the "mix and match" system. However, as I said, optimally you will want consistency.
Note that if you do work with different brands/genres of amps you can massage the sound of the center/surrounds with cabling to suit. So, while I suggest that the optimum would be one brand/house sound of amp, you can do wonders in matching tonality etc. with cabling. I would strongly suggest you begin with one full set of cables if possible, especially for the center speaker and mains, and work from there.
Finally, the Wavelaunch processor will allow you to integrate the Focus and Whisper with ease in a fashion much more deft than simply putting two different passive speakers together. For instance, if there is a difference in output between the two amps you can adjust the level of the Whisper via the processor to match the Focus SE. No problem. You can even tweak the filters a bit to get the various frequencies to sound the way you want. It's one of the speakers which allows pretty much total control, so one is not as dependent upon the "perfect" matching of amps as with other speakers.
If you wish to converse further, perhaps considering your other system components, feel free to contact me. :)
