help me to understand the gain

oNHWY61,
The problem is`nt the Zu`s high efficiency(often a big plus). Again it`s not too much power or current, excess gain is a entirely different matter.Elizabeth uses very inefficient (84db) speakers and has the same issue. It`s gain folks.

I not saying what the problem is, I'm offering a solution. If he keeps the Zu speakers he should redo his preamp/amp. If he gets rid of the Zu, he just needs new speakers. Which is easier and less expensive to implement?

Agree with the resistor change in the pre-amp or the
attenuator suggestion.

Chuck

Gte, you have TWO problems. First is that you have about 130 more Watts of power than you'll need for your Zus. Second is that your poweramp has about 30dB TOO MUCH gain. Too much gain amplifies preamp noise (and the thermal noise inherent in the resistors in any attenuators) excessively and resticts volume-control movement. (At 12dB, your preamp does NOT have too much gain.) DIYaudio.com recently issued a newsletter about gain structure. I can't find it online; if you'll e-mail me at jeffreybehr(at)cox(dot)net I'll forward it.

Nelson Pass, with his FirstWatt amps, recognizes the general problem of too much system gain and solves it with one poweramp, the F4, with ZERO Voltage gain. Read about it at http://firstwatt.com/index.html . It has plenty of power for the Zus and looks to me like a great choice.
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I tried connecting the DAC directly to the amp, the sound is not good. I also try to lower the volume on the DAC. Although it gives a more usable range for my preamp, it has a small impact on the sound. Lowering volume on iTune sounds better.

I think it is usable as long as I use iTunes, but the next thing I will change would be the power amp, or I will get an integrated. I will get the Zu this week and see how it work.

BTW, tube amps are expensive. I want to keep the budget around 1000, and there are very limited choice. Maybe I will start and thread about suggestions.