Right, I've got my SM3s back from Mark now, and have tested the balance with a couple of tracks he's sent me so we're both singing from the same hymn sheet.
I tested using the SM3s with both Sensorcom tips and the Jays single flange tips.
In the case of the Jays, vocals that Mark had heard as right-biased were centred perfectly. With the Sensorcoms, however, there was indeed a slight offset to the right.
I believe this down to fit issues. Unfortunately, while the Sensorcoms give me the bext sound quality of all tips, I do think they can be a bit of a bugger to get perfect fits with, and are not consistent in this respect - unlike the Jays, for example, which are plug and play each time and seal perfectly in my ears.
So, I do think Mark may have had a fit problem, rather than the earphones themselves being technically faulty. The fact that I sent them off for repair and he had the same issue with the returned pair might back that diagnosis up, I dunno, its hard to prove either way.
But here's the thing - at the same time as I have been testing the SM3s, I've also had chance to AB them against my Ety HF5s, And I much prefer the latter, it has to be said. The clarity of the HFs just crushes that of the SM3s. There's a weight and solidity to vocals, a crystal sense of them within the music that the Earsonics don't produce, whatever EQ I apply to my J3.
And that for me - more than soundstage or bass or anything else - is the deal breaker.
It feels really weird and a little guilty of me to be praising a £70 iem over a £300 one, especially as I was a former primo advocate of the more expensive set, but thats the way it slices for me folks. I have to be honest and report what i hear.