I own two low-wattage pushpull amps: a 5 wpc amp using two 349 tubes per channel and a 4 watt amp using two 45 tubes per channel, and I own a parallel SET amp that puts out 6 wpc from two 2a3 tubes per channel. All of these amps deliver adequate levels of power for my 99 db/w speakers. I do suspect that I am hearing some slight compression from these amps running out of gas (sound becomes a bit muddled and lacking in clarity) only when I play choral music at high volume.
If the Reference speakers turn out to be substantially lower than 92 db/w in efficiency, there may be some concern with having adequate power from low-powered triode SETs, such as ones utilizing a 300b tube. SETs utilizing higher power tubes, such as the 845 or 211 tend to be a bit more costly and I would be a bit concerned with any "bargain" amp that is operated at the higher voltage levels required for such amps.
With respect to some of the amps mentioned above, I have heard the Art Audio PX 25 and Jota amps used with several different speakers and I like these amps; I don't know if they are "bargains," but they were good sounding. I have also heard an Audio Space pushpull amp that was very good for the money both in terms of sound and quality of construction. I heard two different Decware amps (I can't remember the models) that were in a shop as trade-ins. I only heard them briefly in a setup that was hardly optimized to show them off, so I don't have any sort of solid take on these amps; what I did hear was quite disappointing--too lifeless and wimpy sounding.
My experience with more reasonably priced SET amps is somewhat limited, but from what I have heard, it would not be that easy to achieve better sound from such amps than what the Manley Mahi will deliver without paying substantially more for the SET amp. Good SET amps are not cheap (output transformers have to be bigger and more expensive than pushpull transformers to perform well),and higher powered SET amps using transmitting tubes or parallel output tubes are particularly expensive.
Also, I would suggest trying an output transformerless (OTL) amp with the Reference speaker. While Reference speakers are already quite lively sounding, a good OTL would ramp that quality up even more and that would be something special.
If the Reference speakers turn out to be substantially lower than 92 db/w in efficiency, there may be some concern with having adequate power from low-powered triode SETs, such as ones utilizing a 300b tube. SETs utilizing higher power tubes, such as the 845 or 211 tend to be a bit more costly and I would be a bit concerned with any "bargain" amp that is operated at the higher voltage levels required for such amps.
With respect to some of the amps mentioned above, I have heard the Art Audio PX 25 and Jota amps used with several different speakers and I like these amps; I don't know if they are "bargains," but they were good sounding. I have also heard an Audio Space pushpull amp that was very good for the money both in terms of sound and quality of construction. I heard two different Decware amps (I can't remember the models) that were in a shop as trade-ins. I only heard them briefly in a setup that was hardly optimized to show them off, so I don't have any sort of solid take on these amps; what I did hear was quite disappointing--too lifeless and wimpy sounding.
My experience with more reasonably priced SET amps is somewhat limited, but from what I have heard, it would not be that easy to achieve better sound from such amps than what the Manley Mahi will deliver without paying substantially more for the SET amp. Good SET amps are not cheap (output transformers have to be bigger and more expensive than pushpull transformers to perform well),and higher powered SET amps using transmitting tubes or parallel output tubes are particularly expensive.
Also, I would suggest trying an output transformerless (OTL) amp with the Reference speaker. While Reference speakers are already quite lively sounding, a good OTL would ramp that quality up even more and that would be something special.
