Buying an amp first and using a receiver as pre/pro is a common and perfectly sensible approach -- in addition to spreading out the cost of going to separates, it allows you to get much of the benefit of separates with a single upgrade. The Paradigm's will probably benefit some from the 755's additional power and headroom (my Paradigm Studio/60's did when I switched from powering them with an Outlaw 1050 receiver to an Outlaw 750 amp). The HK 230 does have preamp outputs, so the setup will be pretty painless (aside from the exertion required to unbox the 755 and set it in the rack).

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review