Neglecting room effects it can be calculated that a pair of such speakers powered by 35 watts will be capable of producing a maximum sound pressure level at a typical listening distance of 10 feet of about 95 db. That is easily loud enough for the great majority of listeners for the great majority of recordings. If your listening includes recordings having particularly wide dynamic range, however, meaning a particularly great DIFFERENCE in volume between the loudest notes and the softest notes, you may have a problem on brief dynamic peaks.
Some well engineered classical symphonic recordings that have been subjected to minimal or no dynamic compression fall into that category. Examples being many of the Telarc orchestral recordings of the 1980’s that were notorious for their high volume bass drum beats. On the other hand, most pop and rock recordings are compressed such that they have vastly smaller dynamic ranges, and you would have no problem with them, or with most other recordings of other types.
So there is no "one size fits all" answer. Personally, I have many classical recordings in my collection having very wide dynamic range, and if a speaker/amp combo cannot comfortably produce 105 db peaks at the listening position (on recordings that I listen to at an average level of perhaps 75 db) it would be a non-starter for me. But as I say the ability to produce 95 db peaks at the listening position will be fine for most listeners for most recordings.
As a point of information, btw, if the speaker can in fact handle 150 watts that would increase the 95 db figure by just 6 db, to 101 db. And to perhaps less than that, if that amount of power would cause the speaker to undergo significant "thermal compression."
Regards,
-- Al