Matching preamp output to amp

[goodolpg]

I have an NAD 1700 preamp/tuner. It has "normal" and "high" output jacks.
I've been using it with a Crown XLS 2000. I called Crown and asked which preamp output to use and they said to use the "high" output.
Today I decided to hook up the Rotel RB-990BX that's been hardly used since I bought it maybe 3 years ago.
Any suggestions on which outputs I should use from the NAD?
High output or normal output?
Earlier I turned on only the Rotel and let it run for a couple hours (no speakers attached either), mostly to make sure there was no sparks, smoke, or excessive heat, all seemed well. Listening to FM at low volume now, I don't want to turn up the volume before I know which preamp outputs to use.
Thanks for any help.

ADDED---some specs, hope they are the needed specs...if other info is needed I can probably find it.
Rotel Input Sens 1.0V/33kohms
Rotel Input overload 5V

NAD Output Imp. Normal 600 ohms
High 150 ohms

 

[avionic]

Try either one and use the one that sounds the best to you.

 

[goodolpg]

So, there's nothing wrong with using either output, no damage would result?
Guess that's my main concern.
I am using speakers that drop down to 2 ohms but the Rotel is supposed to have high current capability.

 

[damacman]

Nooe, no harm wifi befall your Rotel - use whichever gives you the best range of the preamp's volume control.

 

[Blue Shadow]

And Avionic has another correct answer.

The two outputs, 10V max at 600Ω or 15V max at 150Ω doesn't make a hill of beans and most anything will be happy with one or both. Your amp doesn't care so listen and use the better sounding one. If they sound the same use the one that lets you put the volume control where you like it.

 

[goodolpg]

Thanks everyone, I appreciate the help.

 

[DEAFASABAT]

And Avionic has another correct answer.

The two outputs, 10V max at 600Ω or 15V max at 150Ω doesn't make a hill of beans and most anything will be happy with one or both. Your amp doesn't care so listen and use the better sounding one. If they sound the same use the one that lets you put the volume control where you like it.

Best range of the volume control: Power amps can have input level controls for this reason. As long as the amp including input controls is properly designed and implemented, using them should not degrade sound quality.

Input and output impedances: Isn't the rule of thumb basically the power amp input impedance should be about 10x or more that of the the preamp's output impedance?

But, as Avionic wrote, what matters is sound over specs. Let the ears be the judge...