I have been wanting to tri-amp these speakers for a long time but have never been able to scrape together enough mad-money to buy 6 channels of amplification and an active crossover. A few weeks ago I picked up a non-operational Marantz SR7400 AVR at a garage sale for $20 including 5 working ProCinema speakers. I was able to repair the AVR and I noticed that it had something called 7.1 Mode which accepts output of an external 7.1 multichannel decoder. After looking at the manual and doing a few tests I now realize that when in 7.1 mode I basically have 7 channels of 105 watt/ 0.08% THD amplification into 8 ohms. Once a volume level is set in 7.1 mode, the AVR "remembers" the volume and mode even after the AVR is unplugged for several hours. So my thought would be to run this in 7.1 mode and plug it into switched power.
Now I'm trying to think of what can go wrong with using the AVR as my 6 channels for tri-amplification. Clearly, if the AVR gets flipped to any non-7.1 mode where signal is present, my tweeter and mid-range could blow. I'm thinking that I need to install shorting RCA plugs in all inputs and short across both FM antenna inputs. That way, if somehow if gets into a non-7.1 mode it will not have any signal to amplify and blow my speakers. What else could go wrong?
As for an active crossover, I'm thinking of an Ashly XR4001 - 4 way stereo active crossover. I like the XR4001 as I have the option of running my sub in addition to the LE15A/375/075, and one pair of channels can go beyond the 8kHz limit of the other models (it goes to 24kHz). The down side it that these are no longer in production and so I will need to buy a used one. My backup plan would be two XR1001s. Thoughts?
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