Here is an excerpt from John Atkinson’s Measurements section for your speakers…
“The One.R’s impedance is specified as being "compatible with 8 ohms." The solid trace in fig.1 reveals that the impedance magnitude ranges between 3 and 6 ohms for much of the audioband, with a minimum value of 3.1 ohms between 290Hz and 390Hz. Like the original One, the One.R’s use of a passive high-pass filter with a low corner frequency means that the electrical phase angle becomes increasingly capacitive below that frequency. Although the impedance magnitude rapidly increases below 100Hz, mitigating the effect of that phase angle, there is still a combination of 4 ohms and –48° at 100Hz, which will require a good 4 ohm–rated amplifier to drive the speaker to acceptably high levels.”
This doesn’t scream tube friendly to me and almost certainly not for a lower-powered tube amp as it will easily be forced into operating out of its comfort zone. Makes a lotta sense to just start with a tube preamp and then decide if you wanna spend $$$ on a higher powered tube amp. Hope this helps, and best of luck.