I have been using an Onkyo 939 with Mirage OM14 front, OMC-1 and M 595-is surrounds for 12 years, but now the receiver has started to malfunction, so I have bought the "child model", 989, for a very good price. This has 7.1 amps, so I want to use that. But space is a problem behind the chairs (I walk behind the chairs to get to the next room), and even the Nanosat and other Mirage rear speakers are hysterically expensive in Norway. So I thought maybe I could use a set of Alpine SPR 13 C that I have from an abandoned car audio project. Would that work, or is it a bad idea? The wall is double and built like a speaker box, filled with insulation, as sound proofing.