I am getting a new DSL100H and I have read that it needs a boost in order to play songs from bands like Metallica, Megadeth, Anthrax, so I would like to have some advice from fellow guitar men.
Scott Ian used the old TC Electronics Line Driver/Distortion with his Marshalls. Metallice used a Ratt on Kill 'Em All as a distortion, Tubscreamer on Ride The Lightning to push a Marshall and ditched overdrive for the rhythm on Puppets onwards. The ZW-44 (or as it is named now the Berserker overdrive) is clear and has great, grinding highs that help get that sizzly thrash tone on any good, high gain amp.
I'm not sure I understand acemans post but let me pass on my experiences with that amp. The DSL 100H is a freakin monster and I play a lot of 80s glam and 70s hard rock(KISS,GNR,Motley Crue) and I'll tell you u might not need one. That amp has a lot of gain on tap and you should be fine. My best advice is to spend some time testing out the channels and dialing in your perfect tone. Trust me u will have all the gain you will need. However there is difference between all amp gain and an amp with an overdrive in front so if you find the amp's sound isn't enough get itself an sd-1 or the digitech screaming blues