The lower power 300B amps with about 8 wpc are the true SET types. As you go up the power scale, some may be parafeed type amps or push pull type amps. Any of them can be very good, depending upon the design and execution of the product, and how well it fits into your system's needs.
With 89db efficient speakers, I think you'd be best to look at the push pull types with the higher power ratings(40wpc). Some 300B tubes are very expensive, so consider this when buying an amp with multiple 300B tubes in the circuit.
You may also consider using more efficient speakers(95+db) to give you more flexibility in choosing a lower power amp. This is a common path for SET users. Lowther, Fostex, Coral Beta, Diatone, AER, and REPS are single driver speakers that are popular with the SET crowd. Also Jordan drivers with a tweeter are another popular driver setup.
Speaker efficiency is your friend, when dealing with low power amps.
With 89db efficient speakers, I think you'd be best to look at the push pull types with the higher power ratings(40wpc). Some 300B tubes are very expensive, so consider this when buying an amp with multiple 300B tubes in the circuit.
You may also consider using more efficient speakers(95+db) to give you more flexibility in choosing a lower power amp. This is a common path for SET users. Lowther, Fostex, Coral Beta, Diatone, AER, and REPS are single driver speakers that are popular with the SET crowd. Also Jordan drivers with a tweeter are another popular driver setup.
Speaker efficiency is your friend, when dealing with low power amps.