I'm about to purchase a used Denon AVR-887. My question is will this be a decent receiver to power these speakers and also should I set it up as 6 or 8 ohms? thanks.
It depends on a few things Jason, including your preferred maximum volume level and if you run a sub. The impedance trace of the Vienna Acoustics Mozarts (
here) shows a dip below 4Ω at 43Hz and swathe below 4Ω from 100hz to 400Hz. If you run a sub, the dip at 43Hz is out of the picture straight away. If you run a high enough (120Hz) crossover to the sub, the impact of the lower part of the "swathe" will be reduced. If you like to crank it up and listen at loud levels, the AVR may struggle to swing the required current into the low impedance load at those mid to upper bass frequencies. This will be exacerbated if you don't run a sub. If this does eventuate, you could solve the problem by adding a stereo amp to power the front channels. However for the probable cost involved, you could've got an AVR with beefier amps. If you only ever listen at moderate volume levels, there's unlikely to be a problem.
Jason, I wouldn't recommend buying that AVR anyway, mainly because it cannot receive and process the lossless audio codecs available on Blu-ray (dts MA; Dolby TrueHD). Do you have a budget figure in mind for an AVR?
You should leave any AVR set at
8Ω. In short, what a "Low Z" (4Ω or 6Ω) mode generally does is engage a circuit that significantly limits the output voltage of the AVR. This is simply for the purposes of
continuous full power heat dissipation testing by the electrical safety product certifiers (e.g. checking the unit doesn't get too hot to touch). This mode effectively limits the voltage available to the speaker but greatly increases the risk of clipping the amps due to them being "gelded". The
latest Audioholics AVR review even says:
NEVER use the low impedance setting regardless of your speakers impedance!
