Biamping with a tube and SS combo

Read your owners manual and see what your speakers support. To bi-amp, the mid/tweeter drivers (and their portion of the crossover) need to be electrically isolated from the woofer and its section of the crossover. You DON'T want the output of the two amps commingled. 

There are also some setups that need an active, electronic crossover that goes in between the preamp and the two amps. The amps then connect directly to their drivers without using a passive crossover. (This is only correct for a two way system. If you have a three-way, there will still need to be a passive crossover to separate the signal for the midrange drivers and tweeters. An option to this is to tri-amp, where you use three stereo amps.)

You'll also need to have some way to adjust the volume of the respective amps -- it is unlikely that both amps will have precisely the correct amount of gain for proper balance between the mid/tweeter and woofer. The polarity may need to be switched on one of the amps in order to have a correct transition between the upper & lower frequencies.  

This is just a basic primer. As you can see, there is a lot to consider.  

As for pairing a tube amp with a SS amp, that's fine assuming the power and sensitivity aspects are appropriate. It will then just become a matter of your taste as to whether it provides the sound quality you're looking for.

@arafiq
"...I described above with the more common tube pre + SS amp combo? If you have compared both, which one sounded better to you?"..

Having tried all scenarios mentioned above, I’ll mention results can vary quite a bit when you start intermixing different type, brand, and power amplifier outputs. Getting attenuation right without introducing other components can be tricky. There is something to be said about selecting components originally designed and voiced to work together.

In my case, I locked in on a specific tube preamp I really liked (starting baseline), and then tried different amplifiers (Tube and SS) over several years. Also bi-amped the tube amp(s) for top-end and solid state on the bottom end as you described. After I was done screwing around too long, went back to two mono tube amps (same, brand, type, power) to drive each speaker individually. I liked the tube preamp and class A/AB ss stereo amp combo 2nd best.

Kiinda like asking what vehicle to buy, and more info is needed to understand how you plan to use it. It really depends on what you are really trying to accomplish and what starting gear you are working with for your SS amp, and go from there. A lot of people do use tube preamps to change the sound of how a SS amp sounds. Once they get a taste of what good "tube" sounds like, curiosity sets in further about tube amps... :).  Next a series of questions develops about what integrated tube amp they should buy.  Rinse and repeat.  Good Luck.  

Depending on where the crossover point is, there can still be quite a bit of midrange info coming through woofer, which I prefer to hear thru tubes.  I'm doing vertical bi-amping with two tube amps, but am using tubes that are adept at tighter deeper bass for the woofers, and different tubes with better mids and highs for the top end.  Then I run a powered SS subwoofer from 40hz down.  

I too have tried many of these configurations and have speakers with quite a bit of midrange information (even a crossover around 150hz goes really far up if its a first order slope).  Unfortunately, I always lost too much coherency for it to be worth it. The different amps muddied the woofer to midrange crossover and the music fell apart. *This was even true when the amps were identical and fed with the same (split) rca input.* Even with perfect gain matching and identical circuits, just using independent circuits for the woofer and midrange/tweeter created enough differences that I eventually went back to a single amp per channel. I do, however strongly believe in monoblocks with separate amps and power supplies for each channel. And I do have separate amps for my subs.

Obviously plenty of people love their biamped systems, but just be aware that YMMV. 

I've seen Bi-wiring make a difference when there was a cable size issue, I've seen good single runs with good jumpers, work well also.

Bi-amping, I personally think it's the best of both worlds.
I use valves 300hz and up.
I use SS 300hz and down.  300 hz is pretty high, do a tone burst from your phone. It's pretty high..

Depends on your crossover, if it's a 2 way system, it's usually to high, to make a "GOOD" difference. 

Happy Holiday

Regards

Thanks everyone for such informative posts. As I mentioned earlier, I wasn't aware of this specific configuration and was intrigued. Appreciate the education. Right now, I'm enjoying my Luxman 590axii integrated amplifier, but I'm thinking down the line I would like to add a tube preamp in conjunction with the Luxman and see how it affects the sound. I don't think I will pursue the setup I mentioned in my original post. I'm not as savvy or knowledgeable as some of you folks. It's much more likely that I might end up making matters worse.

I have a tube preamp feeding sonically transparent solid state amplifiers and enjoy the combination a great deal. Perhaps I'm biased because of that, but I believe you've made a good plan.  Plus, preamps often run tubes more conservatively than power amps, so it's likely to reduce your tube costs to put them in that location.

There are plenty of relevant threads to review, just search for tube preamps recommendations and you'll see an overwhelming number. My personal impression after investigation was to focus on 6sn7-based designs (e.g., users seem to universally praise Supratek and Don Sachs pres). Although less popular for manufacturers due to microphonics and noise issues, there are also a lot of dht adherents out there as well. I'm about to get one to try against my idht 6sn7 pre.

Anyway, good luck with the search, it should keep you busy for a while...