Helllo Tmesselt.
Speakers are highly dependent on room acoustics, placement AND amplification.
Speakers demand proper matching to an amplifier, due to widely varying driver impedance curves, sensitivity, reactance and bass damping.
E.g, planar speakers need lots of current; horns like low power AND low noise amps; low efficiency speakers need very high power amps (both voltage and current).
Most ported speakers require an amplifier with a high damping factor, however sealed speakers actually sound worse with a highly damped amp.
Room size is also an important factor when selecting the speaker/amp combo.
In summary, my "methodology" is as follows:
-Choose a speaker that matches your taste, room size, acoustics and your loudness preference.
-Then buy an amp that drives that speaker REALLY well.
If you upgrade the amp first you may be forced to change the amp when you decide to upgrade the speakers.
Of course the source and preamp are extremely important.
I agree with Soix and Audiofeil, dollar-for-dollar you get the greatest improvement by upgrading the speakers, however, "garbage in, garbage out", the source is very important, though one needs to spend mucho dinero to hear a small improvement in digital playback.
IMHO the weak links in your system are the USB connection to the DAC (lots of jitter) and the speakers, because Paradigm speakers are voiced for home-theater use. HT requires powerful bass and dialog intelligibility, therefore most HT-oriented speakers have underdamped bass and a peak in the voice range. I hear that in my friend's Paradigm speakers. They are excellent for movies, so-so for music.
If I were in your shoes, I would use an SPDIF digital input to the DAC (to reduce jitter) and install two dedicated AC lines, one for AC-polluting digital server + DAC, another one for the amps. This will clean your digital signal and pollute less the AC feed to the amps.
Then I would start looking for better speakers.
I have owned a Mc402 amp and an Mc275 MKV, I have also auditioned Pass amps several times. I am sure that Mac and Pass amps wil give you the fullness and correct timbre that you are looking for, but not with an USB-connected digital source or with your present speakers.
I hope this helps and is not taken as criticism.
Good luck
