I think at this point if you hate the amplifiers, they are not going to be your cup of tea.
I did notice that mine took quite a while to break in, and they went through many changes, but you should have a general sense of what you are going to end up with right now. Highs might smooth out and extend a little bit more and bass will get tighter, but outside of that I don't think its going to completely 180.
Its also not a power issue. At 4 OHMS, your amplifier is likely putting out plenty of wattage and current.
Also, I would be willing to guarantee you that the amplifier section of the Plinus can't hold a candle to the amplifiers you have now in terms of power and current output.
The amplifiers you have right now, assuming that they are close to kismet, and going to be very neutral; and exactly what is in front of them is exactly what you are going to get.
That means that the quality of surrounding components is going to play a huge role in what you are hearing.
I am not sure what you are going for, but I would think that your allotment priorities are a little askew.
The Plinus integrated retails for 4200, something close to the Kismet from Klaus in monoblock form new would also be around that (3-4K).
Spending all that cash on an amplifier to power it with a 1100 dollar all-in-one preamp/DAC/Amp combo is not very efficient, and is likely leading to your displeasure.
Like many have stated, you need a new preamplifier.
If you can't swing a new preamplifier at this point, I'd recommend returning that amplifiers and getting the stereo version of the Stratos, which will still have more gusto then the 30 pound amplifier section in the Plinus, and use that money to purchase a suitable replacement to your preamplifier section.