After 20+ times trying to switch from MWave4 to Mwave1 I finally did it. MWave1 of Premier is better overall than MWave4 of P300, even when P300 was plugged into Premier.
My DAC1 was hardwired into P300 Power Plant with Valhalla power cords going in and out (2 meters total). It was using Magix levitation feet and 30+ sheets of ERS Paper. I had that plugged into the Premier, bass was crazy.
Amp with MWave4 too = Crazy bass
My GCC-100 amp was plugged into Premier, then I plugged it into P300 by adding a JuiceBar, stock cable and step-up transformer into the path. Bass was the craziest ever, very full and huge. But then I heard some muddiness and boominess, it reminded me of AKG vs Sennheiser. It was the boominess that made bass so full and huge!
So one last time I did a long test between MWave1 vs MWave4 of the P300 Power Plant.
Final test, MWave4 vs MWave1 of P300
MWave1 of P300 made it brighter, edgier and colder, there was more surface clarity but the low-level details were cut off, I couldn't hear them anymore. The impressions were the same as in the past year of A/B-ing.
When I switched back to MWave4 the surface clarity was toned down which made the low-level details more apparent. I heard new low-level details everywhere and it sounded more like real life. It is similar to QuickSilver Contact Enhancer where you tone down the brightness to make details more apparent.
Was MWave4 just a band-aid for bright sound? It would explain why it's a great match with Valhalla cables. With muddy cables you need MWave1 to boost up the surface clarity, because with muddy cables you won't be able to hear the low-level details anyway.
MWave4 of P300 is still way better than MWave1 of P300. But the problem was muddiness on the surface layer, it was unbearable. After my system had been turned on 2 days it got very muddy and I had to unplug it, the P300 Power Plant was the problem.
Using MWave1 of P300 made it sound too bright and harsh, and using MWave4 made it sound too dark and muddy but with more low-level details!
MWave4 was masking the harshness of P300.
Moving DAC to Premier (50cm Valhalla power cord = 4 times shorter)
So I moved the DAC1 from P300 into Premier and it solved the problem, no muddiness on the surface anymore! The harshness is also gone, P300 was adding harshness to the sound, removing it from between DAC1 and Premier made it super smooth. The surface layer is clear, open and smooth, it gives the illusion of more airy sound.
The low-level detail isn't emphasized anymore, but it's still as good as with MWave4 of P300! The surface layer is emphasized now, and there is more surface detail than ever before.
But bass isn't crazy anymore, it sounds more neutral now, it's a little boring but at least there isn't any unbearable muddiness anymore. It seems like this is how K1000 are supposed to sound like, the P300 + MWave4 was just boosting up the bass to compensate, but it was sacrificing surface clarity to do that.
Conclusion
Overall the Premier + MWave1 is better than Premier + MWave1 + P300 + MWave4. Adding a 2nd power conditioner into the path makes it worse, even when it has thousands of dollars worth of tweaks!