Pre/Pro or dedicated preamp

I am cureently using a high end Sony receiver as a preamp in a 2.1 stereo music system in my bedroom. Power amp is the Odyssey Khartago. Speakers are Vienna Acoustics standmounts, with a Rel B2 subwoofer. Source is the most recent Sony SACD player. Power conditioner is the Hydra 4. A pair of Audioquest cheetah RCA connectors is used between the SACD plaayer and the Sony. Shunyata Aries RCA interconnects are used between the Receiver and the Odyssey Khartago. The subwoofer cable is the middle cable in the Synergistic Research "Rel" active subwoofer cables.Speakers cable is Synergistic Research signature 2 - X series active.
Power cables : Audience Power chord "e" from wall outlet to Hydra. Acrolink 7N 4030 from Hydra to Sony. Acrolink 7N 4030from wall socket to Khartago. Neotech 10 gauge power cord from Hydra to SACD player.Room treatments are Real Traps for 2 rear corners and home-made items for first reflections
The system sounds very good. I wish to replace the Sony with either a dedicated pre/pro or a dedicated preamp to provide a substantial sound quality improvement over the Sony. With a budget of $1500 I am prepared to purchase a used unit. A wide and deep soundstage is something I value very much. Bass management & Audyssey etc are not important to me. I want hard core sound quality.  Have not auditioned any replacement prospects. A Marantz pre/pro or the Bel Canto pre 3 have received  good reviews in the press. What other products should I also consider? I really would appreciate advise from experienced audiophiles.