Depends how power-hungry your speakers are, and if they have high-order (18 dB/oct and 24dB/oct) crossovers. If the true Theile/Small efficiency is less than 87 dB/watt/meter, and if the crossover is high-order or employs notch filters, sorry, tube amps are not ideal. Class AB or Class D transistor with 100 to 200 watts is what the speaker wants.
On the other hand, if the speaker has a true Theile/Small efficiency of 90 dB/meter/watt, and the crossover is low-order (6 dB/oct or 12 dB/oct), then tube amps of 35 watts/channel look good. A pair of PP EL34, 6V6, KT66, or KT88 will do the job just fine ... that’s the vast majority of vintage and modern tube amps.
SETs with 8 watts or less ... well, you really do need efficient speakers, and 6.5" to 8" woofers matched with 1" dome tweeters do not qualify. The true Theile/Small efficiency of nearly all 6.5 to 8-inch midwoofers is in the 86 to 88 dB/meter range ... and the woofer, not the tweeter, sets the efficiency of the loudspeaker. There are no magic cabinets that raise the efficiency of the woofer ... the T/S parameters set the efficiency of the woofer, and the entire speaker.
P.S. More complex crossovers are sensitive to source impedance, otherwise called Damping Factor. A very low source impedance, or high Damping Factor, is the hallmark of big-watt transistor amps.