"I've tried a couple different sets (none over $300) and also a keyboard amp, and have not been happy with the muddled sound they have all produced especially in bass chords.
If you want more volume, first try setting Keyboard Touch to -2 and you will be surprised how much more you get.
I came to this EXACT same conclusion, the default setting is not ideal, you get a lighter touch, more clarity, and , no compromise in sensitivity with minus 2 (my preferred setting) The difference in sound is actually fairly dramatic, from slightly muffled to clear. The ability to tweak this is fantastic, like a new keyboard!