300B which way to go?

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.

I aggree with Twl, I have had 3 different 300B amps over 10 years matched with horn speakers. The liquid midrange that 300B are known for are best heard with efficient speakers. I gave my horns to my oldest daughter and currently use a push pull tube amplifier. My current speakers are 92 dB senstitive and I am thinking about trying out another SET amplifier but concerned that my speakers may require more power than a 300B amp can furnish. In my experience the Western Electric 300B is the best overall 300B I have heard, it does it all. Audio Electronics, a division of Cary Audio makes a wonderful afforabale 300B amp, it's a great place to start. Best of luck, it will be an adventure.

I vouch for SET 300B amplifiers. Lower wattage, but the midrange is nothing but magic. How it has been well said, you need to have efficient speakers. I myself have an Assemblage 300B Platinum circa 2001 (a DYI division of Sonic Frontiers, before closing shop.) I use a pair of WE 300B matches tubes with a horn loaded Fostex speakers Sigma 208 drivers 8" with an efficiency of 96.5db. I have these speakers spiked up and for the great majority of recording, I was pleasantly satisfied, but because I have been used to bass, I added a powered subwoofer ( a very fast one with enough amp power) now, I enjoy SET midrange and highs with SS low end slam. Still not quite like a gigantic speaker set with a hugue Amp behind it, but the magic in all different types of music is simply wonderful.
Can easily fetch a decently parted 300B amp like mine for about $1200 without the Western Electric tubes, which will run you a good $500 per pair, used
PAUL

Check out Coincident speakers,(Isrial Blume) , At 97db. the "Victory" and the "Total Victory" allows the use of any amp from flee power SET on up.
http://www.coincidentspeaker.com/speakers.htm.
These are well designed multi driver speakers with high impedance (good for tubes) that can reproduce large scale music or lite jazz with ease, and can do it with 8 watts.
No need for a seprate sub ether.
Here is a website review if your interested.
http://www.high-endaudio.com/RC-Speakers.html
Regards,
Tony

Thanks for the tips! Sounds like I can get away with maybe a 40 watt amp, with 89db speakers, but I might miss a little bass. But perhaps it doesn't matter as 90% of the sound comes from the midrange.

The impedance curve of the speaker will matter more than efficiency. Efficency determins loudness but impedance curve can determine the amount of distortion.

Most SET amp have high output impedance that will interact with speaker impedances. So you want to look for for a steady speaker impedance > 6 Ohms through out frequency range with low phase angle. Every speaker manufactor should be able to furnish you with this information.