I'm not sure I can help with the middle level, but I was thrilled when I moved from MH-750 biwire (with the junction box) to Nordost SPM...
I have had much better luck with MIT IC's (source to preamp is where I liked them the best...).
Without more details, that's my 0.02
I have had much better luck with MIT IC's (source to preamp is where I liked them the best...).
Without more details, that's my 0.02