[mbriex]

  I'm not very kean with technical specifications and have a question for specialists:
I'd like to use a Conrad Johnson preamplifier on my Ref 9V2.
This preamplifier has Gain: 28.5 db, Maximum output: 5.5 vrms and
Phase inverting like most conrad johnson preamplifiers.
Is it a problem with Nuforce amplifiers?
Are there any impedance mismatching if I use four Ref 9V2 for bi-amping (they will share the preamplifier outputs)?
Thanks for your help 

[nuforce-casey]

Nuforce V2 amps are phase-correct.   Therefore, to use it with any phase-reversed preamp, connect the speaker cable in reverse.

[mbriex]

Thanks for this answer but what about maximum output and Gain?
Is it OK for Ref 9V2?

[nuforce-casey]

Hi,
That's fairly typical of preamp.  Nuforce P9 can swing 8V output.  However, gain of 28dB is considered high in modern day's specification.  P9 has a gain of 6dB.   Most preamp has gain of 5dB to 20dB.   20dB used to be the standard in the 'pre-CD era', and lower gain seems to be the norm in 'post-DVD era'.