I'd argue the moreplay is a great preamp full stop. The Ref 5 se is largely regarded as one of the best preamps ever made and for moreplay to compete with it at 1/10 the price is utterly insane.
What I noticed with moreplay in the system is a bigger more 3d soundstage especially with respect to depth and height, more forward and textured mids (incredible with female vocals), a warmer more pleasing tonality. I really can't believe it. This is also with stock tubes and cheap cabling (the ARC has much more expensive higher quality cabling). Moreplay just brings my system to life and although the ARC is good it makes it sound flat and somewhat lifeless.
I plan to do a full review at some point. I will keep listening but right now I don't really get how this is possible.