[Coll]

I have a power amp that has a sensitivity of 1.42 volts and impedance of 10 K ohms with RCA and XLR inputs.
I am looking at a pre amplifier which has an RCA output of 2.05 volts at 75 ohms and XLR output of  4.1 volts at 150 ohms.
Will it be best to use the XLR output even though its voltage is high or should I use the RCA output at the lower voltage.
I have not purchased the per amplifier yet.

[ricardojoa]

Not an expert on the this, but with a high output  voltage on the xlr, you will drive your amp to full power very soon. It means that with little volume, the sound will already be too loud. Some amps have a gain feature, so that you can reduce the gain.
With your example, i think the rca may be better.

[Roger A. Modjeski]

I have a power amp that has a sensitivity of 1.42 volts and impedance of 10 K ohms with RCA and XLR inputs.
I am looking at a pre amplifier which has an RCA output of 2.05 volts at 75 ohms and XLR output of  4.1 volts at 150 ohms.
Will it be best to use the XLR output even though its voltage is high or should I use the RCA output at the lower voltage.
I have not purchased the per amplifier yet.

Those numbers alone aren't sufficient without further qualification. I think the preamp maker is saying he can put 2 volts into 75 ohms and 4 into 150 before it clips. What would be interesting to know what distortion is has into a 10 K load (your amp) and how much it will put out into 10K. As for the sound being too loud that is a matter of preamp gain, source voltage, amp gain and speaker sensitivity.... and of course how loud you listen. If it is too loud we make an attenuator. PM me if you need one.

I will say that a preamp that can put 2 volts into 75 ohms is pretty healthy.

[G Georgopoulos]

 As for the sound being too loud that is a matter of preamp gain, source voltage, amp gain and speaker sensitivity.... and of course how loud you listen.

+1 

[Davey]

That 75/150 ohms would most likely be the output impedance......not the maximum load it can drive.
Those are typical numbers designed to decouple capacitive loads and provide a bit of protection should the RCA tip be accidently shorted to ground.

Cheers,

Dave.

[Roger A. Modjeski]

That 75/150 ohms would most likely be the output impedance......not the maximum load it can drive.
Those are typical numbers designed to decouple capacitive loads and provide a bit of protection should the RCA tip be accidently shorted to ground.

Cheers,
o
Dave.

I could see it being either way. We need to see the whole spec. However 2 volts is pretty low in your case. I am assuming it puts out a lot more voltage unloaded, I hope it does and if not I wouldn't want such a limited output.

[G Georgopoulos]

I have a power amp that has a sensitivity of 1.42 volts and impedance of 10 K ohms with RCA and XLR inputs.
I am looking at a pre amplifier which has an RCA output of 2.05 volts at 75 ohms and XLR output of  4.1 volts at 150 ohms.
Will it be best to use the XLR output even though its voltage is high or should I use the RCA output at the lower voltage.
I have not purchased the per amplifier yet.

Matching preamp to pwramp,how is that work,i havent got a clue,someone explain to me what is that..
is it amplification?what is it? joking..