Experiences with miniDSP 2x4? Noise?

I have been using a Minidsp 2/4 balanced for several months now. It is imo the most significant upgrade to my system I’ve yet made. I use the bal outs of my Mcintosh C41 into a Classe CA 101 and a Classe 100. They power custom speakers : ported full rage rolled off at 250 Hz and LF transmission lines that roll on at 250. 
I use REW and MiniDSP’s usb mic + cal file. I find the system to be very clean. Additionally you may opt to use a higher quality power supply and mount everything in a 1U rack chassis with xlr and usb panel mounts, LED + power switch.  The unit has jumpers that control input sensitivity that may come in handy. 
I use REW for analysis only and have found the quad filters to be not too good so you may choose to dial in your own EQ based on repeated measurement. 
My source marerial is both digital and analog Marantz CD and Oracle Delphi tt with custom mc cart with saphire canalever. I listen to classical, jazz, rock... and if I find something that is well recorded, it sounds amazing. Sorry for the late response but I just saw your post today. 
Cheers

I just found your question and just received my MiniDSP today. It was very easy to set up and use. I did not hear any noise at all. It produces sound even more real with better imaging than the ART CX311 active crossover that it replaced. I should have purchased the MiniDSP first. I am using a Pioneer Elite AVR as my preamp, Carver M-1.0t MKII opt2 amps with my Magnepan IIIas.