My 6.3 also same problems as you when work on first day, but after run in it is another world, 8.3 also more worse than Heco, which driven by LX90, after change to XPA-5, the whole system sound like another world, so you should try using XPA-5 or other power amp with strong power to push your 6.2 ,4 ohms speaker need more power to driven (the Emotiva designs are 4-ohms is because they are using dual 8-ohm woofers in parallel, which creates a 4-ohm load.)