Want to run a 'sub' to complement my Markbass 2x10 (8 ohm, 400W + tweeter). There are two options: A Marshall 1x15 (same as Chris Wolstenholme uses, 8 ohm, 200W) or a Peavey 1x18 sub (42-1000hz, 400W 8 ohm). The Amp is an Ashdown MAG 250..(250W into 8 ohms) min impedence 4 ohms. What's the best combination.. and do I need a crossover? If I get a bigger car could I run all three and if so which two in series (the combination going in paralell with the remaining speaker)? Will something go pop fizzle?