I can't comment on whether or not the 990 would be an improvement over your RSX-1056. I can say that the 990 does sound very nice with the RMB-1075. Before the 990 was released I demo'd the Outlaw Model 950 against the Rotel RSP-1068 and RSP-1066 through my 1075. The 950 was the hands down winner. (At least to my ear it was.) I've since upgraded to the the Outlaw 990 which was an improvement over the 950.

hope that helps...

later,
simp
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Marantz av7005 Proc.
Oppo BDP-83
Rotel RB-991 (mains)
Outlaw Audio Model 2200 (center)
Rotel RMB-1075 (ss, rs)
f, B&W DM604S3
c, B&W LCR600S3
ss, B&W DM302
rs,Polk M3II
HSU VTF-3 MK3
APC H-15 Power Conditioner
Display: Panny PT-AE4000 Proj. + 92" DIY Screen
Little Dot MKIII Headphone Amp
Denon AH-D1100 Headphones (needed a quick, cheap set. looking for an upgrade worthy of the h/p amp.)