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I read the manual for my RIIA amp. It is a schiit mani but this may be applicable on many other riia:s.

 

I discovered in at schiit home page that the lower the gain are set then the better performance will be given to you! 

 

The schiit gives at 30dB 

THD: <0.005%, SNR: >90dB

 

But if I use the standard MM mode a 42dB 

THD: <0.008%, SNR: >82dB

And so on..

 

I use a passive preamp so if I go with the lower gain at 30dB and then I only need to turn the volume potentiometer more and as long the sound levels are sufficient I do not care. If the volume knob is at 11 o'clock or 3 o'clock..

 

So now at 30dB I utilize better the RIIA preamp and enjoying the:

THD: <0.005%, SNR: >90dB

Instead! And the full value/performance are utilized of the RIIA. 

 

http://www.schiit.com/products/mani

Gain 1 = L, Gain 2 = L (Decca Mode)
Gain: 30dB 
THD: <0.005%, A-weighted, at 1V RMS
SNR: >90dB, A-weighted, inputs shorted
Crosstalk: -75dB, 20-20kHz
Sensitivity: 9mV for 300mV output
Overload Margin: >20dB

Gain 1 = L, Gain 2 = H (Standard MM Mode) 
Gain: 42dB
THD: <0.008%, A-weighted, at 1V RMS
SNR: >82dB, A-weighted, inputs shorted
Crosstalk: -75dB, 20-20kHz
Sensitivity: 2.3mV for 300mV output
Overload Margin: >20dB

Gain 1 = H, Gain 2 = L (Low Output MM/High Output MC Mode)
Gain: 48dB
THD: <0.01%, A-weighted, at 1V RMS
SNR: >80dB, A-weighted, inputs shorted
Crosstalk: -75dB, 20-20kHz
Sensitivity: 1.3mV for 300mV output
Overload Margin: >20dB

Gain 1 = H, Gain 2 = H (MC Mode)
Gain: 59dB
THD: <0.03%, A-weighted, at 1V RMS
SNR: >70dB, A-weighted, inputs shorted
Crosstalk: -75dB, 20-20kHz
Sensitivity: 0.3mV for 300mV output
Overload Margin: >20dB

 

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9 minutes ago, trott3r said:

Does the lack of gain mean you have to introduce distortion with you amplifier though?

Just wondering.

Yes you are right! You will get a lower signal level/strength to your preamplifier. That level will be needed to be "in some cases" more amplified to get the desired level to your power amplifier/s.

 

But as long you do not drive your preamplifier to hard into that it will start to get into distortion. Then I think/guess you will be fine.

 

I wrote above "in some cases" that if you use a active preamp that utilize a active amplified output stage. 

 

When you use a passive preamp that is just a volume potentiometer (and perhaps input selections) the only thing between your RIIA and power amplifier is a set of selected able resistors that are the volume potentiometer. So if you select x ohm or y ohm before the signals go to the power amplifier will not effect anything as I see it.

 

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So in summery:

If your RIIA data sheet tell you it has better performance the lower the gain is.

Then go for the lowest gain setting you can use without getting into so that the preamplifier are distorting or clipping!

 

Than you have lost sound quality and gained nothing..

 

With other words if you use the preamplifier volume knob at 40-50% and lower the RIIA gain a notch and then you need to turn the volume knob maybe to 60-80% instead. To get the same sound pressure level as before. But now the signal that are going into your preamplifier are having better SNR and THD.

(Warning! But be aware that do not have the volume knob cranked up so far when you switch to another source on your preamplifier..)

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