Lott's of good, interesting answers, my advice is try as many amps as you can, having an amp, that you can play along with a CD/MP3 player, is a nice option, I have 2 amps that have that feature, a Fender Rumble 500 head & a Mesa Boogie 800+, the Mesa has really good tone shaping capabilities, the Rumble has a kinda baked in tone, but very usable, I also have a Ampeg SVT-CL, but you don't have any silent/headphone play a long abilities, and the 80+ pounds of weight, can be a hindrance, if you don't have help, I did have the Aguilar ToneHammer 500 some years ago, ( used it for trade bait, on another amp ), and once you get familiar, with how the drive control works, it's a very nice/good versatile amp, I don't have any expedience with GK, or Markbass, so I can't comment, on those products, but I'm a believer, in "the cabinet, is a big part of your sound concept", so pay attention to how cabinets sound, as they play a role in tone shaping, I'd say as to cabinets, go modular, meaning 210's or 2 12's, or 15's, you can scale up when needed, or scale down, plus, it's easier to move and fit into a car/SUV/Truck, and you don't have to purchase it all at once, and it give you the ability to "Mix and Match" cabinets ( as a side note one of the best mixing of cabinets is the Mesa Boogie Subway series of cabinets, as there designed to be mixed & matched, other brand, it hit or miss ... IMHO ) ... hope this helps
