SET amp recommendation

Based on your speakers and price point, I think a used 300B is probably the most likely candidate for you. I don't think you will be happy driving your speakers with lower powered SET amps 45/50/2A3.

Another potential option is to keep checking ebay as periodically Sean Casper offers F2a amps in that price range. The Siemens F2a tube (made famous in German Klangfilm amps in the 1950's) has about the same power rating as the 300B but has a completely different sonic signature. It is a much more dynamic sounding tube with better bass. It also has a wonderful presence to it - it comes across as a much more powerful tube. What it does give up to the 300B is some midrange sweetness and a bit of nuance. Both would be very good alternatives to your OTL.

Great information! Thank you

If the 12 ohm load of the zeroformers remains relatively flat a 300b amp would love this load. If the amp has "good" quality transformers and P.S. as audiofeil mentioned earlier, I believe 91db speakers in a smaller room at normal listening levels will be fine. 1500.00 budget does limit choice to some degree(good transformers and P.S. are`nt cheap).

I have used my 300b SET amp with 89 db speakers(8 ohm) in a friend`s system(large room) without any promblems what so ever.

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If the 12 ohm load of the zeroformers remains relatively flat a 300b amp would love this load.

As long as you can live with the loss of power. I believe these calculations are correct.

from 12 to 4 ohms is 3:1 for the impedance ratio

take the square root of 3 to get the voltage ratio = 1.7

If you have an 8W 300B amp you have 8V at the 8 Ohm tap (8V squared divided by 8 ohms = 8W)

divide that 8V by 1.7 to get 4.6V which will get you a little over 5W max.

maybe, but that's not a lot to drive a speaker with a recommended power of 50W.

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Herman,
This much I know, my speaker is a 14 ohm load(94db efficient) and it is a splendid match with my 8 watt amplifier, sound levels usally 75-85db(in a 14x26x8ft room)If his speaker is truly 91db efficient and he listens at modest levels(his stated preferenc)i.e. around 60-75db range the speakers are only drawing fractions of a "watt" of power.
He says his room is small, With a good quality 300b amp he will be fine.

It`s my understanding/experience that tube amps like a higher ohm load that`s relatively flat.
Charles