Upgrading from Primaluna

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?

You could consider upgrading to a newer PL setup.  I bought EVO400 separates last fall, and I fall more in love with the whole rig every day.  Hoo whee!