I have some experience with Prima Luna amps. But not with your speakers. It seems you speakers do not have a high efficency. That is no problem if the impedance is fairly flat. If the impedance goes below 3 Ohm then I would advice you to buy something else.
You can call Kevin Deal at Upscale Audio for advice.
Kevin was in on the original PL design.
Given your speakers, so much will depend on how loud you like to listen.
I own the PL2 and the PL5 and have used them with speakers that have ranged from 85db efficient to 90db efficient. I listen at moderate levels, but there is enough left to go louder if I wish.
Personally, I would go with the PL Premium and mostly because of my good time with the PL2. I have owned PL products since 2005 with zero issues.
Mainly i listen at moderate volumes. I would like some headroom for the occasional mood of pumping it up though .
Skip the PrimaLuna and go for Mystere. This is the high-end division of the same company. You don't pay any more for the upgrade but you may be happier in the long run. From my experience, you don't Mystere equipment for resale (at least not yet anyway). Check out the Mystere pa11 ($1995) or pa21 ($2995).
I'll second Rich on Kevin Deal. He's a PL dealer (I believe that he was, and may still be, the PL importer) so he'll be wearing a sales guy's hat. Nevertheless, - IME - Kevin's a pretty straight shooter and a good guy.
BTW, I've had PL mono amps for several years. Reliable, great sounding, great fun w/ plug 'n' play tube rolling.
I have heard the PrimaLuna amps with ProAc speakers, and it is a nice combo. You list some of their newer models here though, which I am not familiar with. I have a Dialogue 2 integrated and like it very much. I have heard it and a few of the older models on the ProAc Studio 140's, which I think have a bit more efficiency than the ones you list, but I am not certain of this.
Pl 's website does not list specs ? All the amps listed are close enough in price to be in my price range . Why so many in such a close price range ? I will take the advice and try and reach kevin deal. I did submit an inquiry with PL yesterday , waiting for a email back or call from Pl.
I know this in not on topic, but you can buy a used pair of Quicksilver V4 in yur price range. They are a great match with your speakers, especially with EL-34 tubes.
Assuming you buy Primaluna amps try them with EL-34 tubes. The Response 2.5 are not very efficient so I would get the most powerful Primaluna that will run EL-34 tubes.
I believe all PL amps will run almost... any tube due to the autobias . A big reason i am thinking of going with them !
The autobias feature is very nice indeed. I will say I prefer my Dialogue 2 with EL 34s instead of KT88s.
I recommend you choose the most powerful in the series if you are going to buy Primaluna. The autobias feature is great. I also have Proac Response 2.5 and I think you will be happier selecting the model with the most power.
My listening room is almost the same dimensions as your and I have the Prologue 6. My speakers are 92DB and I've never been more contented with an amp, however, I would get the 7 since it's newer. You can change tubes to fit your mood with these amps.
Skip the PrimaLuna and go for Mystere.
Have you heard any of the PrimaLunas? Will you speak to the primary differences between them?
I've owned PrimaLuna equipment before. I bought the PL Prologue Three preamp and used it for six months before trading up to the Mystere ca11 preamp. The PL preamp incorporates an ultra-linear design configuration while the Mystere uses a push-pull design configuration with 6SN7/5AR4 tubes. For me, the Mystere was a better fit given my other equipment. I kept having issues with the PL not playing nice with other equipment. When I powered up the Mystere, all those conflicts went away. I continue to use the same equipment today which includes CODA solid-state amplifier, Manley phono stage, Rega Planar 25 turntable (Dynavector 10X5 cartridge), and Totem Sttaf speakers. If you have an opportunity to listen to both amplifiers - PrimaLuna and Mystere,I would satisfy that curiosity, because in my experience, the high-end division of the same company didn't cost me any more but the outcome was night and day. Hope that helps!