Hi Mike, I don't think any of us can answer your question, we can only offer clues from our own experiences that may help you find YOUR answer. Here is a summary of my experiences.
I've been in this hobby over 40 years and have owned many different types of speaker. I finally settled on a design that pleased me for the past 19 years, until I changed those this past summer. My long-term speakers were a large, floor standing design that offered a full range response with very good soundstaging and tonal accuracy. They were rated at 90 dB and were touted to be "easy" to drive. But they were also rated at 4 ohms and their load dipped below 3 ohms at two point on the spectrum. Therefore, they were difficult to drive and I tried many different amps, SS and tube, medium and high power, before settling on 800 wpc mono blocs.
Within the last few years, three of my friends changed their systems to speakers of 97 dB or higher. As we frequently visit one another for listening sessions, I came to two realizations. First, high quality efficient speakers seem to offer more sense of "aliveness" than less efficient speakers, all else being equal (and here I would agree with those who suggest at least 97 dB to truly be considered efficient). And second, even with efficient speakers, amp matching is important to insure adequate power -- one of these friends progressed through a series of amps from about 4 wpc SET to about 16 wpc PPT and each power increase resulted in a more musical presentation.
Influenced by these listening experiences I sold my long term speakers and bought a pair of Cain & Cain BENs, rated at 97-98 dB. I'm still experimenting with amps but I've reinforced the idea that 15 to 20 wpc are needed to simulate live music experiences, even with such efficient speakers.
The other factor of course, and as others have mentioned, is the size and acoustics of your listening room, the type of music you listen to, and your preferred listening levels.
But my summary conclusion is that SS/tube/SET/PP/OTL etc. is not the critical factor. Finding speakers that suit you best, then searching out the best matching amp for THOSE speakers will be your key. Good luck and have fun along the way.
I've been in this hobby over 40 years and have owned many different types of speaker. I finally settled on a design that pleased me for the past 19 years, until I changed those this past summer. My long-term speakers were a large, floor standing design that offered a full range response with very good soundstaging and tonal accuracy. They were rated at 90 dB and were touted to be "easy" to drive. But they were also rated at 4 ohms and their load dipped below 3 ohms at two point on the spectrum. Therefore, they were difficult to drive and I tried many different amps, SS and tube, medium and high power, before settling on 800 wpc mono blocs.
Within the last few years, three of my friends changed their systems to speakers of 97 dB or higher. As we frequently visit one another for listening sessions, I came to two realizations. First, high quality efficient speakers seem to offer more sense of "aliveness" than less efficient speakers, all else being equal (and here I would agree with those who suggest at least 97 dB to truly be considered efficient). And second, even with efficient speakers, amp matching is important to insure adequate power -- one of these friends progressed through a series of amps from about 4 wpc SET to about 16 wpc PPT and each power increase resulted in a more musical presentation.
Influenced by these listening experiences I sold my long term speakers and bought a pair of Cain & Cain BENs, rated at 97-98 dB. I'm still experimenting with amps but I've reinforced the idea that 15 to 20 wpc are needed to simulate live music experiences, even with such efficient speakers.
The other factor of course, and as others have mentioned, is the size and acoustics of your listening room, the type of music you listen to, and your preferred listening levels.
But my summary conclusion is that SS/tube/SET/PP/OTL etc. is not the critical factor. Finding speakers that suit you best, then searching out the best matching amp for THOSE speakers will be your key. Good luck and have fun along the way.