First question, as always, what's your budget?
Second question is if you are intending to hook up some of the speakers to the receiver or if you are going to connect all speakers to an external amp. If you are using an external amp for everything, you are better off getting a dedicated processor (such as Marantz AV7702/AV7703 or Anthem AVM60 if you choose that direction). The processors will have much better power supply and analog output sections. The only question is how 4K "current" you want the processor to be and how many bells/whistles you want.
As far as voltage output, 1V is not a lot and I would say most receivers will have no problem with this. There may be some amplifiers that require 1.4 to 2 volts for maximum power output. If you really concerned about amplifier gain, then get a dedicated processor/amp combination that has XLR inputs/outputs and use balanced XLR cables for signal. XLR has an additional 6db gain and the volume will be louder.
If you are still looking for a receiver, there is generally no difference in the preamp section between models of receivers. For example, preamp in Marantz SR5011 is not going to be any different than preamp in Marantz SR6011. The difference would be power supply for the amplifier section of the receiver. At this point, you would have to choose the brand that offers the sonic signature you are after. Marantz, Yamaha and Anthem will all have different sonic signatures.
