I used to have a Yamaha DSP-A3090 Integrated Amp that also had front "surround" speaker output (it's a Yamaha thing). I tried with and without and it's basically just an effect.. works well with all the trillions of DSP modes Yamaha receivers come with.
You either like it or you don't but is certainly worth a listen.
Neht24
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HT: Samsung 61" DLP, Arcam AVR250 Receiver, Denon DVD-2910 DVD Player, LG BH100 Blu-ray/HD-DVD Player, Atlantic Technology ICTS-6LCR "Tilting" In-Ceiling Speakers (Left/Right/Center), Atlantic Technology ICTS-8.2e In-Ceiling Speakers (Surrounds), Atlantic Technology 10e CSB Powered Subwoofer and Universal Remote MX700 Remote.
2-Channel: Arcam FMJ C31 Preamplifier, Arcam FMJ P35 2-Channel Amplifier, Arcam DiVA CD192 CD Player, Monitor Audio Platinum 100 Monitors w/Stands and REL C-305 Subwoofer.