I was struggling with the inbuilt drives on the POD (which are ok but ultimately fairly average - the TS, Tube Drive and Tube Comp are decent) as I was trying to get a nice, natural Marshall tone. I was getting closer but it had no bark or no nice compression and growl so I thought stuff it, I'll run my pedals and see how it takes them. I ran my Kingsley Minstrel tube preamp pedal (it's a proper plate voltage tube preamp in a pedal) in the loop and then out front and wow, what a difference that made. It's producing a killer Marshall tone now. The loop worked ok but in front it provides a more open and dynamic feel and it drives the HD sim really naturally. Whether it's ACDC, Randy R or Iron Maiden, I feel I now have Marshall tones fairly well covered. The Fender stuff is already good so now I need to dial in the Recto tones and tweak the Vox Brian May kinda sounds. TBH, the Marshall tones I have now are much superior to my old 11R rig and are the closest 'Marshalleque' tones to a real Marshall I've personally heard (live) from a Modeller (IMHO). The rig provides a killer low volume practice sound too. Starting to be quite impressed with this little amp.