Applying those recommendations of power to speaker efficiency in real life can be very difficult. While most, but not all, power amps do meet their stated specifications on power output, the same is not true at all for speaker specifications. In fact, rarely do speakers meet their specs, running 2dB to 6dB under specs.

I was thinking in terms of a PSE SET being almost double in power relative to the same single tube per channel SET. With the 45's, it is still low power, though.

Both of those points are well-taken and both open up a can of worms. Some amps work well with speakers they shouldn't be able to, while others have difficulty dealing with speakers that are sensitive but might present difficult loads.

Rated speaker efficiency is a whole other racket. A lot of published speaker efficiency ratings bear little resemblance to reality. Others are so band-limited as to be unusable (such as only above 500hz) while still others use "in-room" efficiency numbers that rely on room gain to meet numbers.

I wish that we could all rely on a standard such as 100hz - 12khz, +/- 3dB, at 8 ohm impedance with no less than 6 ohms. This accomodates virtually the entire musical range and provides a meaningful standard.

Nothing set in stone. Dennis is considering a limited run of 45 PSE amps along the line of AA's/Straitwire's amps. He doesn't have a real details yet but if it is something you might be interested in I would let him know. I am going to take the bait. As much as I love the SEP PSE when I hook the 45 SET back up there is something special happening, in my setup. My speakers are 96dB sensitive in a relatively small space and the 45 SET does not lack punch or volume. What it gives up to the SEP PSE is control over the woofers which leads to some overwhelming bass issues I initially attributed to room resonances. My hope is the 45 PSE will give me some the woofer/bass control of the SEP PSE while retaining the magic of the 45 SET.

Interesting. I've never come across a high sensitivity speaker which I've fallen in love with. So I don't know what I'd do with a low wattage amplifier. My current Inspire is rated at 17wpc and that's a bit on the low side for my "perfect" setup. Good enough for 90% of my listening.

I think that if we accept 92 - 94dB as an acceptably high sensitivity speaker then the compromises we often find with very high efficiency speakers become less common. I've also found that once we get above 90dB with benign impedance amplifiers as low as 5wpc can work depending on the room. I've owned or heard a number of speakers like this that fall into this category. The only caveat is that powerful bass with a low powered amp is not something we are likely to encounter.

I am not certain of the sensitivity spec for my speakers. In their original form it was 91dB. Which might mean they would measure at 89. I had them factory upgraded to be nearly exactly the same as a new model which was spec'ed at 94dB. Who knows what they would measure at? 91? 92?

I do know that when I was driving them with a 260 wpc SS amp in a large room a few years back, I drove the amp into clipping! Twice! I still have this amp and use it on occasion.

I am much more careful with my 17wpc Inspire. I'm in a smaller room and sit closer to the speakers. I listen at lower levels than I used to. I have heard it gently clipping a couple of times.

I'd rather have more like 50 wpc, but don't know of any which capture the realism of a high quality single-ended amp. My Inspire 17 watter sounds fantastic and can play up to a volume level which meets my needs about 90% of the time.

My desire for one of each in every color is going to get really pricey.🤑

Please keep the other topics under discussion. I'm always interested in you all's POV. These speaker sensitivity and new DH designs are of particular interest.

I do have something that is bothering me of late. There seems to be so much bling on new tubes. I do not care that my tube base is white or copper or ceramic,... A ridiculously large gold lion printed on the glass is just gaudy. Does black vs grey vs blue glass really matter that much to the sound. Quality manufacturing, high, sustainable vacuums, a solid pin and base structure,... these are important to me in that I feel that along with a good design lead to the best functioning/sounding tubes. The rest seems like just so much fluff. Am I alone in thinking that to much is being invested in cosmetics by tube manufacturer's of late?

I hope this is not to incendiary for the rules here at AAf.

IIRC you have a pair of VR7's. These were rated at 92dB/2.83V. But the impedance was 4 ohms below 200hz, which means that in this region it is an 88dB speaker that also has some significant current demands. This is not a speaker I would think to be friendly to SE tube amps. If the speaker had a high, flat impedance it would be better suited even at the same impedance. Harbeth speakers are lower sensitivity on paper but do much better with tube amps.