How much higher is hard to say since it's so subjective. I just think you've got excellent speakers that would justify and greatly benefit from higher quality amplification. And if they're rated at 4 Ohms it's a good bet they drop below that in at least one point along the frequency curve. One example of a higher level integrated would be a Pass Labs INT150 that's for sale here listed at $3700. It puts out 150W and doubles into 4 Ohms that I think your Dyns would appreciate, and it operates in pure Class A up to 10W that would probably be where you'd do most of your listening. I think this could be a great fit both for your speakers and your listening preferences, and it should be much more than an incremental improvement over an H100 or H80. There are several reviews from Stereophile, Positive Feedback, 6 moons, etc. that would be worth reading. I think it's more on par with the quality of your speakers as well. It's like buying a sports car -- you could put cheaper tires on it and it will still run, but it's capable of providing much better performance with better tires.
The Halo is a nice recommendation, but the treble is likely to be a little hotter than the Pass. Not sure if it would be too much or not -- that's entirely your call, but the risk of you finding the treble irritating is probably higher with the Parasound.
I think you're greatly limiting your choices by requiring an onboard DAC. And the way technology is changing I'd recommend buying a standalone DAC, which would also give you more choices there as well. For better or worse.