Took delivery of my Vision Ears Stage 4s a few weeks back and have been getting familiar with them.
Similarities with References
My previous reference are ACS T1s, and in my set up, the Stage 4s are cut from a very similar cloth, sound-wise. Like the Stage 4s, the T1s have a broadly appealing sound that features a somewhat boosted lower end, yet despite this neither pair over-emphasize one frequency range to the detriment of the others. The presence of the boosted bass results in an almost paradoxically smoother sound, perhaps due to the smaller drivers of cIEMs. To me, this gives the sense of the music coming from a real space with walls, floor and a ceiling. Other IEMs seem to favor a flatter, more idealized response curve which I feel results in a more artificial sound, as if the music comes from an open field where there is no reverb or sense of boundaries.
Compared to other IEMs I've tried the T1s and Stage 4s have a more even response and consistent performance on a wide-range of music types.
Differences from References
Speed. That's the biggest thing I've noticed in the last few weeks. The Stage 4s simply seem much faster to stop and start, making the T1s sound a little smeared in comparison on more complex passages. For example, Joe Jackson's rapid fire patter on "Got the Time" becomes a lesson in his sneering diction, rather than the race-to-the-finish rocker you've heard for decades. The S4s stops and starts sound very naturally and revealing without resorting to artificial edges or decays. I listen deeper and get more involved in the music, and am constantly seeking out more challenging pieces to listen to since the S4s are never fatiguing.
The soft silicone ear molds of the T1s are better at blocking ambient noise out and result in a more quiet listening environment, but I wouldn't go so far as to say they are more comfortable than the S4s.
The headphone cables for the T1s are permanent where the S4s allows a swap out. The Vision Ears supplied cable is a strong performer on its own, but listening to some after-market cables provided interesting results. For example, ALO's SXC 24 built on the speed and detail of the S4s. Playing Leo Kottke's "Vaseline Machine Gun", it becomes apparent from the harmonics and decay that Kottke is using a glass slide on his 12-string guitar, rather than a metallic one. This is the type of detail(s) you can hear under the highest resolving sources in the best of systems, and I was hearing it sitting in my local vendor's shop from an Ipod/CLAS/RX-3 combo and Stage 4s. Incredible. Track after track, new found detail or ambience surfaces.
A final word:
In dealing with Vision Ears, I have nothing but the highest compliments to pay to Marcel, Amin and company. They have dealt with me directly and fairly and have made recommendations to me which effectively took money from their pockets but which they believed would make an overall improvement in my listening experience. I got an exceptional product, one I am proud to show to my friends, and recommend to others interested in premium cIEMS. The art work is gorgeous, the shells are sturdy, inspiring confidence in the workmanship and the selection of choices for colors were so diverse that I felt guilty having to choose only one color, and a simple one at that. The custom engraved box and peripherals supplied was above what I expected and a slight step above the ACS gear. Finally, the turn-around time from placing the order and sending in my impressions to receiving the finished product was just a few weeks, better than ACS and from what I've read, better than many other cIEMs.
If you are reading this thread to decide if the Stage 4s are for you, I will stop short (barely) of giving an unequivocal "Yes" since you may prefer a different sonic signature than I do. But I would say the VE Stage series should be on a very short list for users looking for a gimmick-free monitor that gives hours of unfatiguing and clear listening. If you have a high-end front end and listen to lossless, you will look far and wide before you find anything on par with Vision Ears for enjoyable listening that can also dig deeper into the music than all but the highest of multi-kilobuck systems.