Source is a PC. If the volume setting is increased in software, the speakers get louder without having to increase the amp volume. I'm wondering if this increases the power draw from the amp to the speakers? It's weird because my 50wpc channel amp seems to be driving my 100w speakers to really loud volumes with the gain dial at about 10%, and I'm worried that maybe my PC is such a loud source that the amp is being driven harder than it should, if that makes sense. PC volume is at 100%, which is +0db. The sound card is fairly high end and apparently doesn't distort at all at this setting. I'm keeping volume at 100% because apparently bitrate is reduced at lower volume, and so is SNR.