The Amarra 4 essentially IS a ULN-8 but (if I'm not mistaken) without the mic preamps - as Ted has already mentioned.
Sonic adds their own EQ and RIAA, where the ULN-8 has Metric Halo's EQ (my personal favorite) and RIAA.
So it is minus the mic preamp hardware, has
different EQ and RIAA software, but is $500
more? Wonder why that would be?
Steve