I initially was really impressed with the improvements done to the Heresy IVs...lower frequency range (58hz to 48hz), cool ports, better internal wire (AQ), better bolt and nut speaker attachment instead of wood screws, better speaker binding posts, etc. Their fit and finish is superb. The new base looks cool also, although you can't dust under it (might not need to). I had them for a couple of months of break-in so I doubt that was the issue. I listen to a lot of piano music, and certain mid-high frequencies would jump out weirdly and harsh my mellow. The IVs simply didn't deliver the coherency from top to bottom I was used to with the IIIs. I tried swapping out the preamp, different amps, anything I could think of and when I put the IIIs back in it was a revelation...the IIIs just work for me. Maybe over time the IVs would have gotten better, or maybe it was just that pair, but I sold 'em at a very small loss and I assume the next guy liked 'em. Who knows? I simply assumed the new polyamide "non throated" mid was the culprit as that's a complete redesign from the IIIs. I'll call Roy Delgado...now where did I put his number...damn...