All my life, I've automatically just plugged into the high input of the amp. (If the amp had a low and a high). Recently, after buying a Vox AC30, I discovered that, for a clean sound, it's best to plug into the low input, and turn up the channel gain (and, if it has one, the master volume). Duh. Should have been doing that for the last hundred years. So much better. Gets those tubes cookin'. A much richer clean tone. Now I only plug into the high output when I want distortion. But y'all probably already knew that. I'm a little slow.