I have a Yamaha RX-Z1 running a 5.1 system with NHT Evolution speakers. Yamaha volume control malfunctioning. Considering replacing the Yamaha with something like a Marantz 7008 or Yamaha 3030 or getting a new pre amp like a Marantz 8801 or Yamaha CXA 5000 and using the old RX-z1 as an amplifier. Alternatively buy something like a Emotiva XPA-5 plus pre amp. Thoughts? Can I use the RX-Z1 as an amp?