Upgrading from Primaluna

" 10ft width and 15ft length so 6ft between speakers and 2 ft from side walls is all I've really got."

With not much to work with other than it is a dedicated space, it suggests almost nearfield setup and those Sopras need to be pushed out 4.5ft away from the front wall, and your already sidewall is near "right"(depending how your measuring)it's actually CLOSER together.

http://www.cardas.com/room_setup_calculators.php

Using the 1/3  it would be around  5' or Cardas calculation above. You should have your chair distanced accordingly.

Rack needs to go either behind you or somewhere on the side.

Depending how those speakers react THEN, is what you're faced with. The DSP thing with a mic to "tell you" what your ears are "missing."  wouldn't invest in anything until you compare results and consult with the room acoustics companies.

You have a Sopra 1 and subs room perhaps to some. IMO, you still will  get the Sopra 2's to "work."

How loud do you like it playing?
If you are not playing it loudly and clipping, then more amp is not going to do a lot.

You might have less distortion. Whether than matters or not is a different question.

Ignore any of the posts that are off topic. Your question was about maybe trying a bhk essentially, I say maybe build a short list of more powerful amps both ss and tubed and find a way to try a couple. Those other posts are full of assumptions.

I think you could benefit from moving your speaker outwards and revisit your front end components. Maybe even going to a speaker that fits your room better. 

…Those other posts are full of assumptions

respectfully I would submit that determining the SPL and maximum power the OP is using currently, would be germane as to whether more power is needed.

Like the OP, I too have a Dialogue Premium HP. It seems to pump out 90 dB(A) as measured with an iPad NIOSH app, at ~9’ in a room that is big in spatial volume… and it sounds “o’roight” doing so.
And my speakers are perhaps a bit less efficient than the OP’s??

There are 2 problems with those Sopra 2 speakers:

1. The load is a bit difficult to drive as. It is low impedance and also the phase angle gets high.
2. The distortion is low, which is good. So they tend have a bit of a quiet sound, and to me they begged for the volume to be turned up.

(When I heard them, they did sound great.)
Hence - with the combo of 1 & 2, I would probably upgrade the amp first.

I assume that the OP is using the 4 ohm tap?
They may also benefit from a set of KT120s if they wanted to keep the PL amp.
Maybe that would allow them to punch a bit harder?