The Mackies I had overheated alot, in fact almost EVERY time I pushed them for any length of time. I doubt that it would happen if I used a separate sub, and kept them up on sticks, but on the floor - near corners, and on carpet ... there is just not a great air flow to keep them cool. Sound is terrific when they are "on". Closest to real studio tone of all 4.
JBL's - a good substitute for the 450's with slightly less high end sizzle. They are also a weird shape to transport, but are a little lighter than the Mackies.
EV sx100a - This is my choice for all around performance. They're easy to stack, carry and set up. They are not as punchy or as brilliant as the other two, but they can be tweaked with pre amps and EQ to an acceptable level. I chose them because of portability vs. sound. They are pretty close in the sound dept, but WAY ahead in the portability dept.
Yamaha's - haven't tried them beacuse they we big and bulky. No sense in going backwards again.
Don is right about those Peavey 15's - they're great, but beastly to carry.
I have a high output party this Saturday, and I'll need to bring my bass rig to round out the EV's. It's a Mother/Son dance at my old High School, and I'll be at least 1/2 a DJ all night because of their ages. I'll definatly NEED the ooomph! I have a Gallien Krueger combo bass amp (12" spkr 150 watts) and a Bag End 15" ext cabt. That works so good to add the extra baSS ON THE FLOOR LEVEL. (stupid caps lok !!!)
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(ok - better now)
If you do the one night stands alot, like I do - The EV's are a great choice, but if you are doing larger venues on a regular basis .... you may need a sub. They are not overlt bass heavy. They DO however, have a nice, natural sound that carrys well in moderate situations.
Best overall sound has to be the UNpowered Mackies, with a powered sub - but That's a bugger to set up, too heavy to carry by one hand, and too many pieces for the average solo act. If I was in a band - I'd use that setup. The Mackie horn has the best, smoothest high end of them all.