Linn Majik DSI into Sunfire 300x2 strange result

I would appreciate any opinions , hints regarding the following scenario I tested the last days and got fuly frustrated. Some background infos first:

My system consists of a Linn Majik DSI integrated streamer (means has own amp) and Wilson Benesch Discovery speakers. Cables are Nordost.

As I assumed the Linn Majik DSI amplification section to be suboptimal for the speakers, I decided to experiment with an external amplifier and picked-up a Sunfire 300x2 opportunity, latest model from 200x (just shortly praised on Arthur Salvatore Readers letters but also on Audiogon). Cable was Neotech copper and I had to use the PRE OUT of the Majik, as this output is the only one subject to its volume control. The WB speakers were connected first on current and finaly on voltage posts, no difference in the phenomenon I will describe below.

For those of you not familair with the Majik DSI sound, I would qualify it as being more on the darker side. Although the sound isn't really bad, I have the feeling that the bass is somehow boomy, uncontrolled.

The result of the Majik+Sunfire combo was an incredible bright/harsh sound with exagerated highs, a more controlled bass, but the highs were so "loud" (even at normal levels) that these seemed to overlay everything. On the other side the Sunfire is known to be an excellent bass performer, ....but the bass was not sooo deep. In a nutshell, I had the impression that the whole sound spectrum was "raised into the higher frequencies" and very agressive.

Switching back to the Majik amp, of course the balanced sound returned.

Any idea if this might be a kind of mismatch between the Majik output and the Sunfire input? Or perhaps between Sunfire and Wilson Benesch Discoveries ( an audioasylum fellow hinted me at an observation done recently by a Sunfire 600 owner that had a very harsh sound with Legacy speakers, a horrible combination obviously). One the one hand I can't believe the Linn DAC/pre section can be so bad (despite its digital volume control) and neither that the Sunfire sounds so harsh/unbalanced...what could be the cause for such a behaviour?

Many thanks to you guys for any hint, opinion...

Adrian