Hi Chris, your amp will be plenty. I ran a pair of the Proac D2 monitors, which had almost the exact same sensitivity as your Studio 100, off an Audio Research VSi55 integrated and I think those are rated for 48wpc. The difference in actual decibels, between a 35wpc amp and 48wpc, is barely enough to move the needle on a decibel meter. And the VSi55 was more than enough amp to play very loudly, loud enough to be uncomfortable. Unless you're putting these in a huge room that is inappropriate for the size of the monitor, your amp will be fine.
I am a bit surprised that there are no posts by those who insist that they get better sound running their 104 db/w speakers with something like 200 watt amps instead of whimpy 100 watt amps.
Most of the amps I like are lower-powered so I agree with the consensus above. I have heard the Tablettes, which are less efficient than the Pro Studio 100s, sound very good in a dealer's showroom that is about 20' by 25'. The speakers are mostly demonstrated with 15 to 30 watt tube amps.
According to Stereophile’s measurements the speaker has a sensitivity of 86db/1W/1m, about 2 db less than specified. It also has a benign impedance curve. The manufacturer recommends amplifier power between 30 and 150 watts.
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."
As with Larryi I agree with the consensus of positive responses. Al raised a point that you need to contemplate, how loud is loud enough for you and do you need 105 db peaks? The 2nd point is what genre of music do you listen to most often! ? These will certainly be influential factors in determining how much amplifier power is sufficient for your needs. As with Larryi I’m sonically more impressed with low to moderate power tube amplifiers.
Thanks all for the helpful and clarifying replies! They all have good points. My room is 3*6 metres with a high roof at 4 metres but I usually listen at moderate levels and seldom at dynamic music. Also sitting pretty close. As a father of two the need for party-levels is reduced! According to Stereophile, the impedance of the Proacs seems to be acceptable for PETA (People for the Ethical Treatment of Amplifiers) :-), and I also like the sonic signature of tube amps, so I will go for the Proacs.