I haven't upgraded the heads on my RS1500 but I do have a repo amp. I listen to the "older" prerecorded tapes in my collection almost every day and the sound is way better than stock. Really, not even in the same ballpark. I'll be sending my headblock in for new 1/2 track and 1/4 track heads in a couple of weeks. I'll do my usual wordy, excessively long, somewhat condescending (but frequently inane) reports on what I think. It should be one hell of a good read!