How many watts per channel are enough?


I am considering my first tube amp (Prima Luna Prologue 5 or Jolida 502 p). I lean toward the Prima Luna but it only has 34 watts per channel. Is that sufficient to drive my Jm Labs Daline 3.1 speakers (rated at 89db into 8 ohm)? My preamp is a Jolida 5 t. The room is 12 by 24 with high ceilings. I listen primarily to jazz and classical at low to moderate volume. Thank so much for any advice.
hugo1
I have to agree with Zd542, the wattage ratings have not been very consistent in my experience. However, I think you should be ok unless you want to play really loud. Is there a way you could audition the amps before buying?
Based on your listening levels, that's plenty. Even in a relatively large room, such as yours, you'll be fine. Especially given the speakers relatively benign load on the amps.
There are a lot of nice used amps with more power for sale;I would look into buying a used more powerful amp.
If it does not work out then resell and not take a big hit in the wallet.
I also agree with Zd542. Watt ratings of amplifiers is like horsepower ratings of cars. It is tricky.
You'll be fine on most recordings with 34 watts, but not on some recordings. And I suspect that a major reason for the diversity of opinion in the previous responses is that people listen to different kinds of music.

Given that your listening is at "low to moderate" levels, the most significant variable is likely to be the DIFFERENCE in volume between the loudest notes and the average notes on the recording. Some well engineered classical recordings which use minimal or no compression will have a ratio of peak to average volumes in the vicinity of 30 db, which means that 1,000 times as much power will be required for brief volume peaks as for the average volume level of the recording.

Most rock recordings, on the other hand, are compressed such that less than 10 times as much power is required for volume peaks as for the average volume level of the recording.

Neglecting room reflections, it can be calculated that at a centered listening position 10 feet from the speakers 34 watts into your 89 db speakers will produce a sound pressure level (SPL) of about 100 db, assuming the specs are accurate. Averaged over a broader set of positions, but at that same 10 foot distance, the corresponding figure is 97 db. "Moderate volume" probably means an average SPL in the area of 70 to 80 db. Many of the symphonic classical recordings in my collection that are especially well engineered, meaning in particular that they are minimally compressed, will reach SPLs of 100 to 105 db at my listening position on brief volume peaks, when played at that kind of average level.

Finally, it appears that although your speakers are nominally rated at 8 ohms, they reach a minimum impedance of 4.1 ohms at some frequencies. That will further reduce your chances of success with a marginally powered tube amp.

Hope that helps. Regards,
-- Al