Hi guys, my problem is quite similar. I have a Line 6 DT25 Combo that has worked fine until now. After the last rehearsal with my band, topology 1,2 3 stopped working. Very (very) littler output, while topology 4 worked great.
I thought a tube change was in order. So I installed new EH tubes where the EL84 was a matched pair. Resteted the amp and tried again and 4 (still) works great. Topology 2 generates normal output/volume - but completely without gain. Topology 1 and 3 are increasingly weak in volume/power. Better than before the tube change. But not at all as I used to. And 1 & 3 are also completely without gain/distortion/compression.
When I switch to low volume mode - everything is like before and works perfect.
Anyone who has experienced the same and found a solution?
