Loop the soundcard. And put the input level on 1 and output level on 100(Windows, Mac may be different.). I am talking system volume. SLowly lower the volume level and see what happens while watching the oscilloscope and runnig a sinewave. You can watch THd at same time. See whats happening. After trying this, lower output and rasie input, doing same thing. Your computer may have a sweet spot
You need to measure 2.83V across the 8R load resistor placed across the speaker terminals. THat is 1W of output from the amp. You do not need 2.83 out of the sound card. I am thinking you will need about .5V
Can't you change the output of the soundcard in your distortion program?
Of course you have lower distortion with 2V over the 8R but you should go to 2,83V.
I suppose you will come to 0.02 %, still a very good value.
Gonna connect the amp to the "stero" and listen for a couple of days.
Is the Spdif out any good quality on that EMU 0404 USB?
I did not have the usb 0404, but the pc version of the EMu 1212. They make good soundcards, so it will be very good. Is it HiFi? I think its best not to go there. Its a long, expensive path that usually involves spending lots of money on the last 15% of performance, only to realize that evrything is a tradeoff and you will need 4 amps, 3 dacs, 6 speakers, 5 preamps and 24 sets of cables to get it right.
