Re: Talk to me About Mesa Boogie Rectifier amps
Im thinking about getting a MARSHALL JMP1 Rack system + a POWER AMp(need to figure out which one will tgive the marshall more tightness and bass to couple with marshalls brightness and mids)
Based on your signature and that video I'm assuming that you're into pretty hardcore metal. Rack systems tend to work great for that style, but a JMP-1 doesn't have all that much gain and is more suited to classic metal (like Iron Maiden). Taking a further step back, you need to ask yourself if you're prepared for the complication, expense, and weight of a rack system. Being located in Brazil the biggest issues will probably be a combination of expense and rarity; I'll price a few sample systems in USD to illustrate.
Excellent rack system:
Preamp(2U): CAE 3+SE ~$1500
Poweramp(2U): Fryette 2/90/2 ~$1500
Effects(1U): TC G-Major 2 ~$300
Switcher(1U): Voodoo Lab GCX / Ground Control Pro ~$500
Power(1U): Furman PL8 ~$100
Rack Case: Mesa/Boogie SUS4 10U ~$400
Cheap (but still decent) rack system:
Preamp(2U): Soldano SP-77 or Mesa/Boogie Studio Preamp ~$500
Poweramp(2U): Mesa/Boogie 50/50 ~$500
Effects(1U): TC G-Major 2 ~$300
Foot Controller: Rocktron Midimate ~$100
Power(1U): Furman PL8 ~$100
Rack Case: SKB Roto 8U ~$200
You're looking at around $1,500 for the entry-level system or just over $4,000 for the higher end one without cabinets or cabling. Keep in mind that many of those prices are for used gear and may end up being much higher where you're located. You'd also need at least two speaker cabinets, and the smaller rack case fully loaded would likely weight around 30kg; 50kg for the bigger one. In short a rack system can be an amazing rig, but it probably isn't worth it unless you have deep pockets and your own road crew.
I hate to rain on your parade here, but we could probably be more helpful if you explained what it is that you don't like about your 5150III. You may end up being better served by keeping the amp and swapping cabinets, or maybe adding a boost.