Moon 390 Network Streamer

@singere I owned the M400s -I loved them.  I'd recommend them in a heart beat.

Prior to the M400s I was using McIntosh MC-302 (300 watt/ch) and considering upgrading to the MC-462 (450 watt/ch).  I listened to the 330a and I preferred them to the MC-462 hands down and listening at similar volumes.

I decided to purchase two M400s versus 330A in order to provide improved control of my speakers because I like higher listening volumes than most (85+dbs).  The decision was easy because 2 M400s cost less than the MC-462.

I expect their sound to be virtually identical when the volume is 75 to 80 dbs - chassis is the same and the only real difference you'll see is number of inputs and outputs  At higher volumes ability to manage musical peaks and impedance variations would favor having the M400s.  (It is twice the power supplies, capacitors, etc.).

Considering the cost and future proofing your system, my decisions would be buy the M400s and 3 quality power cables for 390 and the M400s.  This will be less than the 761 and is an excellent system (I know because I've done it).   

@ over the moon

You're using the 860AV2 in your system, which probably similar to the 761. I need to decide on one of the 3 units (330A. 400M or 761). The difference in price including tax going from the 400M to the 761 is $4,373. One side of me says bite the bullet now versus later.

Once you purchased the 860A V2 was the wow factor versus the 400m significantly better?

There is a significant difference between the M400s and 860Av2. The space between notes is extremely apparent. 

I personally would step up the model line since the cost is still the same. I’d even consider see if there are 860Av2 available and their price.