Where to pad? Interface or Amp?

I'm wondering what most people do with their signal coming out of their interface.  Do you pad the interface signal into your power amp/powered speakers (and run your speakers or amp at full) or run your device full up and pad the amplifier?

CC

I do neither.... normally there is a volume control inbetween so I can adjust as necessary and blow away my ears.

Hmmm...

I figure it this way.  I either have a lot of the signal coming out of the computer interface and not much being amplified by power amplifier.  Or I have a small signal out of the computer interface and the preamp section of the power amp doing a lot of the work. 

I think I'm inclined to run the interface hotter into the amplifier and have minimal amplification from the power amplifiers preamp.

UNless someone can advise me otherwise?

CC

Depends on the thd performance of the interface at full analog output.

You may want to run the analog stage of te interface a few dB down to avoid a rise in THD, then compensate with the amp.

conleycd said:

I think I'm inclined to run the interface hotter into the amplifier and have minimal amplification from the power amplifiers preamp.

Click to expand...

Whatever the position of the volume control on your powered speakers, the gain of the amp section is always the same. The volume control acts as an attenuator between the input stage, which generally runs at about unity gain and the power stages/crossover/EQ which have about 26-40 dB gain.
Typical operation involves a line level signal (0-+4dBu) coming from the monitor section.
Most professional interfaces have  an output level of +18dBu to +24dBu for OdBfs. That means that when playing back a hot track, the peak output will be  16-20 dB higher than the max level the speakers can handle, so you'll need an attenuator capable of 20 to 80dB attenuation in order to have a usable range of 60dB. But now if you have a track recorded at low level but you want to hear it loud, you may need no attenuation at all, so your effective volume control needs to have a range of 0-80dB, which a basic potentiometer is capable of.
Reducing the level digitally (that's what many DAW's offer as volume control) is not a good choice because of the loss of resolution.

Hmmm that's a fair bit to consider.

I'm using a MOTU 828mkii interface.  Which is middle of the road.  The output on the interface is 'digitally controlled.'  I don't know if this means that as I am turning down the volume I'm loosing resolution (I'm not turning down the output fader of the DAW).

I'm monitoring with NS10s and a Hafler transnova p1500 (pretty run of the mill).  I'm not any expert on these kinds of amps.  But the attenuator does not attenuate to nothing - there is always some measure of gain with the attenuators (are they always attenuators?) all the way down.

I figure running my interface at like -60db or something can't be great?

CC

Apparently, the CR output level is adjusted via a digitally-controlled attenuator in the analog domain, so you don't have to fear losing resolution, the A/D always operates at full resolution.
The only optimization you have to do is run the CR output as hot as can be in order to maximize S/N ratio in the analog connection. As hot as can be means without entering into distortion.
I can't find any info regarding nominal and max level of C/R output on the MOTU website, so you'll have to figure out by yourself what range of output level suits you best and adjust the input attenuator on you power amp to produce suitable listening SPL.