Which Distortion for thrash? ADA MP1 or Blackstar ht distx?

[kernowmetal]

Hi all, Im new to this site. I was wondering what you guys think will give me the distorted sound im looking for? I have a Marshall JCM 900 4100 with 6l6's
running through a marshall 4x12 with gt-75's and im not particuarly happy with the overdriven sound from it. I know this isn't the best marshall money                      can buy but at the moment replacing it isn't an option due to cash flow. I am looking for a classic 80's bay area thrash overdriven sound, basicly i want a tone that will recreate a half descent alex skolnick (Testament) to chuck shuldiner (Death) tone. I have a pair of ibanez rg's an rgt42 with a miricleman in the bridge and an rg550 soon to have a pair of nailbombs when cash allows! I have approx £150 to spend on the right distortion unit and was wondering what would suit me best either an ada mp1 preamp through the fx loop or a blackstar ht dual/distx etc straight into the front. I currently run an mxr 10 band eq through the fx loop to try and tighten things up a bit which helps a lot and a boss sd 1 through the front for a bit more bite, but the lead sound doesnt have the class or richness that im looking for. Any help will be welcome. Thanks guys!

[LazyNinja]

SD1 in front and EQ in the loop is a good combination so I'm inclined to think it's the amp's basic tone that needs improving. How long have you had the amp and when were the valves replaced? New valves and a rebias might be all you need.

Haven't tried any of the pedals mentioned so I can't help with that sorry. I'd look at a good OD instead of a distortion pedal because JCM900s already have enough gain.

[Stevepage]

How about trying a Keeley Modded Tubescreamer? I had the TS9-DX flexi 4 x 12 and I'd really recommend it for getting that Testament type of tone as it also has an adjustable low end.