Really? Do you think it's marketing reasons or a specific reason?
The only thing I can think of is output vs input sensitivity on pro amps. I couldn't actually find the output on the 103. However I'm looking at three 2x4 minidsps unbalanced which outputs 900mv and the emotiva upa500 requires 850mv. The XPA series requires 1.1, but then I'd swap up to the balanced kits which output 2v.
I could be completely wrong though lol
Did you decide against using the Oppo BDP straight into the amp? I still think that would be a really cool idea! If I could afford a BDP-105 or if I could find a used BDP-95 then that is how I would be setup! The thing is that those Oppo's never seem to come up on the used market for much under what they cost new! If I ever find a used BDP-95 for a good deal, you can bet that I would snatch it right up! Sure, you would loose any room correction software going from a receiver or pre/pro, but I have a MiniDsp and several Behringer iNukedsp amps coming soon, so that is to me, a moot point. I have absolutely no need for a receiver or pre/pro what so ever.