Need Help!

I’d like to get opinions on running a source with variable output straight into the power amp rather than through a preamp first.

I tried that and found the limiting factor was the noise floor of the source device. I found it was basically the same as running with my preamp turned way up so its gain was 1.0, i.e., same voltage out for a given voltage in. Turning up the output of the source had the same bottom noise just with the larger desired signal on top.

It's worth trying to see if it lowers the noise floor. There are a couple of issues to consider. If the input impedance of your amps is low a device like a DAC could have trouble driving the amps directly without additional noise or frequency response anomalies. Also, you'll have to be careful that the DAC volume control doesn't accidentally go to full volume.