I will be taking delivery this week of a used Aragon 4004MKII (2 x 200w; about 65lbs.)I have $100 avaible to tweak it with either an upgraded PC (like 12 or 10 gauge) or a set of footers (like Vibrapod feet + cones).
Hi-Fi Tuning fuses or a better PC(PC first). The Vibrapods will help, but won't provide nearly as much improvement(unless you've REALLY got some resonance issues) as power supply upgrades. Try to find a good used 10ga PC for max-benes.