This looks nice for something simple. I use to have a cheat 8 channel behringer that cost me around 100 fiat units... It was good and cheap 

 Could be worth a try… but I was just reading about your SV1 and it has a tube in its circuit, as well as built in amp modeling.  So I’m surprised that it isn’t sounding good direct in :-/ 

 Yeah, the tube is there. Not sure if it's used always, or only for the distortion section. See pic.

On headphones it's really good though. https://image.nostr.build/6d662c24bfd202990289363e1abe793b3d1e2ad2a1ad40c5be48c3718d97a0b0.jpg  

 Huh.  I really can’t imagine why it wouldn’t sound good direct.  Are you using balanced TRS cables (as opposed to TS / instrument cables)?