Around here, people refer to upgrades as an Iem of similar sound signature, but better, I believe. I would consider the A73 an upgrade to the VSD3S, with a fun V-Shaped signature. It has more air and a greater soundstage than the vsonic and the ergonomics is better(at least for me). I think the A73 housing is smaller than the VSD3S, and the build quality is better. I really like the build of the A73. I'm hearing my songs differently and I'm loving to go back to the ones I found to get old before, and rediscovering them. The A73 has a similar sound signature to the VSD3S, with less sibilance, more clarity across the whole frequency range, more air and a bigger soundstage, of course at a more premium price. If you enjoyed your VSD3S, I think you'll love the A73. I certainly did.