I’ve been tearing my hair out trying to rectify the squonky nasal sound of my 20 II with picking on the clearer settings. In the end I just bought a Boss Katana but have actually now found the problem. Both my guitars have humbuckers and, if these are on full volume (as I tended to leave them) I get this weird nasal treble, especially on the B string. However, dropping the volume to 8 or below largely fixes this. Of course, a humbucker will distort at full volume and I’m guessing that the little 20 can’t cope with this (my katana 50 is fine with it). And if course, if I really want a clear sound I shouldn’t be on full pickup volume anyway. Anyway, sorry little 20, all is forgiven.
The-in built pre-sets aren’t still aren’t great and I wholeheartedly recommend the settings supplied by Guitar Chalk that I found elsewhere on this forum
https://www.guitarchalk.com/line-6-spider-v-20-mkii-settings/ which sound great
btw I’m using an Ibanez Artcore AAS93 Semi Hollowbody. I also have an Ibanez AFC155 Archtop which doesn’t suffer quite so much - probably dueb to its lower output humbuckers.