How to safely pad the output of a NAD D 7050

I dreamed about 4-way fully active, but if I'm ever able to invest in one, I'm sure there dsp won't be a problem. So 4 channels for now (subs and passive networked mains).

Transparency is most valued property, any coloring is made with dsp/source material. I can't picture myself tuning my system by switching dacs, or cables all the same.

I like the concept of miniDSP products, but are they transparent when used as additional ad/da and after volume control and things?
 
Cheap DSP
the t.racks DSP 4x4 Mini

I have it. I only miss better delay. The smallest steps is 20 cm. It's balanced in/out. It's most likely same quality as your NAD. I'm sure they just use some integrated DSP functions. But, you have a pretty normal setup. Why don't you just use the line out for sub and NC400. If you don't need eq, just use a simple PLLXO. It's a resistor and cap.
 
I’m thinking he might like the flexibility that full dsp allows, but yes the “extra” step of AD/DA conversion - particularly at the budget entry level - is something with which a lot of folks have discomfort.
Only the golden ears of the end user can determine if the net system is “transparent” enough.