I currently am running my Modulus VJ4 through an iamp 350 & 2 Epifani T110 UL's... I love the sound. However, I am noticing that I would like a little more volume and I have the iamp at about 12 noon on gain and volume... Should I upgrade to a lighter, more powerful iamp 500? Will I notice that big of a difference in volume and headroom with only 150 more watts? Are there any tonal differences between the mosfet 350 and the digital 500? If so, what are they?