I was considering a Firebass head, but at 600$, I shopped around. I found a used Peavey Megabass for 350$ with a small rack and speaker cord included (head is ~10 years old). I liked this head quite a bit, only a few scratches and clean inside. Is is a bi-amp with 200W at 4 ohms per channel (400 full range), 7 band eq, and built in chorus. Looking at used gear it sounded good biamped to a used Hartke 210 and used Ampeg 212 cab. I compared this to new amps with comparable power, a Hartke 4000(400W) and a WM4004(400W). The Megabass going thru only the Hartke 210 was louder than both the Hartke 4000 going thru a Hartke 410 and the WM4004 going thru an SWR 8x10 or 6x10? All the heads were rated 400W at 4 ohms, so at 8 ohms they should be close as well in Watts. All of the cabs were 8 ohm cabs except maybe SWR. I would have thought that the larger cabs would have produced more sound, but the opposite was true. Why?? Is the wattage ratings of the speakers the difference? The 210 was overpowered while the 4x10 and 6or8x10 were underpowered. I am new to these larger setups and do not understand how everything works together yet. Any advice is appreciated. Thanks.