Amp for passive pre--more power or higher end?

NAD has some good specs (20K impedance/1.3V sensitivity/29dB gain) for passives. Not as good as Plinius, which would be out of your price range, but better than many.

Do you have any idea of the output voltage and impedance of the Lite DAC? Any specs on the Axiom?

It is beneficial to get an amp with a higher than normal sensitivity. My Meridian 605s only need .5 volt for full output and work very well with passive.

Thanks for your posts

I was not able to get output voltage for the DAC. Based on what I knew, Tim Stinson at Luminous sent me an Axiom with a value of 2.5K (the resistor?). That has worked out great--I got a big improvement in clarity using the Axiom instead of the NAD's preamp. Tim (who was great to work with) said the Axiom I have should probably also work fine with a c272, although it is not the same as c320BEE.

Notice too that sensititity is proportional to wattage ratings. Often, within a manufacturer's lineup, the sensisitivity rating goes down (up numerically) as the amps get bigger. Often, there's a difference in ratings between balanced (XLR) and single-ended (RCA) connections, when that's an option.

Gotta admit that those Meridian 605's are mighty sensitive for 150 watts.

Generally for a passive, the output of the source is critical with at least 1.5V and an output impedance less than 200 ohms being favourable. If there is an impedance mismatch, frequency extremes get rolled off.

Most resistive passives are about 10K input impedance but 100K are available, including some Noble pots which is the brand reported to be used in the Axiom. Higher impedance is an easier load but there are trade-offs.

Then, speaker efficiency plays a part too. So does the length and capacitance of the cables....

What was your question?