Maybe more, idk, but if you look it up the VERY best thing for blocking sound is cement brick. If you have high enough ceilings you could do a quick and dirty drum riser by placing masonry cement bricks next to each other in maybe a 9 brick x 9 brick pattern.
Also, an electronic drum kit is essentially nothing more than mute pads with sensors, so if you have a problem now an electric kit won't solve it. I see people suggesting electronic drum kits however I feel these will do you no good as most good ones use real kick pedal apparatus with a mallot that strikes a stopper pad/sensor. They probably can't really hear much of the actual drum kick sound, they just experience shake, shake, shake. Actually, I just realized you said you already have mute pads on, so it's probably a little more than just half the problem. Do they have problems with the snare, or is it really just the kick? I'd be willing to bet that half the problem is from the pedal stomping rather than the actual kick drum sound.
