My less than 2 cents worth:
Various brands of tubes and also the age and condition of the tube and if the tube is a 12AX7, 12AT7, 12AU7 etc (they might all be a substitute) will not only sound different, but go into overdrive differently. Some are also considered to be more 'musical' sounding than others as well. For critical use, such as recording, I will hook up a preamp to my DAW with the top off and try various tubes in the unit, using the same input signal to find the cleanest and best sounding ones (if clean is what I am after). I do this visually by checking the meters and also by listening to it. I also pay close attention to the noise floor with no signal (no playing but instrument hooked up) going into it to see what the tube does at idle (the cable can add noise too). Tubes can also be run at different voltages and some people tweak with that.
They all respond in unique ways, much like various brands of car tires, and since Alembic can be considered a 'sports car' kind of bass, it's worth doing. Note that some worn tubes or tubes that are of various brands can do worse on the noise test but (especially with guitar) actually sound better! I have some vintage 12AX7 Golden Lion and Mullard tubes that are slightly noisy but sound fantastic!
For new tubes I like JJs. They sound good and are consistent and wear slowly and gradually without just failing all at once so much. On the down side, since they degrade so gradually, it's easier to ignore them as they age. It's worth it to keep a spare new one around just to compare it to one you have been using for a while.
