Passive or Active Pre- Amp for Nuforce STA200

George, thanks for your input. Since I am a neophyte; what is the input impedance of a typical power amp? 

George, thanks for your input. Since I am a neophyte; what is the input impedance of a typical power amp?

There "was" an industry standard of 47or51kohm I wish they stuck to it, and many tube amps went higher at 100kohm, Rogue use 1megohm!!! All these are perfect for any passive or high output impedance tube preamp.

But today, many Class-D amps are 10kohm as are the odd linear amps at 20kohm, some of Nelson Pass’s First Watt amps are this low.
These amps are mostly suited to solid state preamps with low output impedance, there are a couple of tube preamp exceptions.

Cheers George

I had to install a passive attenuator between my Rogue RP-5 and NuForce STA200 since my Zu Omen Defs are 101 db efficient. The tube hiss from the Rogue was a bit much for my taste. Now, when I was using my Project PreBox s2 as the pre (when Rogue was repairing my RP-5), quiet as a mouse. I'm using a Schiit SYS as the attenuator and now have super quiet playback. I'm looking to purchase a Benchmark AHB2 which has 3 gain settings to choose from.