Hi does someone use a mesa walkabout head? how does it sound? is it powerful? On the site it says 300w but they didn't talk about impedance... 4 ohm??? a friend of mine suggested me to try one (and buy it) but the shop is 50 miles away from my home so if someone says it sucks I won't go and try it... I also tried a marshall vba 400... nice sound but... will valves be a problem with volume? I mean, will it sound good if I play at lower volumes or will it suck like guitar valve amps do at low volumes?